There's no doubt that the comicbook movie has been one of the big boxoffice success stories of recent years. Naturally the big budget superhero blockbusters based on the big Marvel & DC Properties are the first to come to mind;
Batman, Superman, Catwoman, Spiderman, Punisher, Hulk, Blade, Daredevil, Elektra, X-Men, Fantastic 4 all within the last 5 years.
Of course there is the stereotype of a "comicbook movie" equalling a "superhero movie". However, a large number of non superhero movies have also been made, with comic books as the source material: Sin City, History of Violence, Constantine, Road to Perdition, Ghost World, Men in Black, Hellboy, From Hell, League of Extraordinary Gentlemen, V for Vendetta, with Frank Miler's 3000 also on its way.
Most people wouldn't realise these films started off as comic books; even the David Cronenberg, the director of History of Violence, didn't find out until quite late in the process that his film started life as a comicbook!
Including sequels, that makes 30+ films just listed above! In addition, there's the TV outings such as Smallville, Blade, Witchblade, Birds of Prey, Painkiller Jane, and cartoons (JLU, Batman, Legion of Superheroes, Teen Titans etc). Then there are also films and TV directly influenced by the genre, including "Super Ex Girlfriend", "Sky High" and "The Zoom").
It is clear that comic books are being used as a massive resource by Hollywood. In terms of multi million dollar franchises we can expect more of the same; Spiderman, Fantastic 4, Hulk, X-Men (or Wolverine at least), Batman, Superman, Sin City and Hellboy all have sequels planned over the next couple of years. When the first of these films were coming out (Spiderman & X-Men) these were seen as big gambles, and it is easy to imagine that if they had not done so well, as "Batman & Robin" and "Judge Dredd" had done in the 1990s then the comicbook genre could so easily have been written off as something that didn't work, and the recent flood of movies would never have happened. Instead the comicbook movie has become a Hollywood staple. Aside from prospective boxoffice returns, it's easy to see the why - as they deliver fully formed exciting concepts, exciting storyboards & concept art (from the original comicbook), and an already loyal fanbase.
An interesting knock on from the Hollywood interest is is a real rise in the prestige of the comicbook world. They are being looked at seriously and this is driving the quality of them up as people enter the newly prestigious field. Screenwriters from shows such as Lost, Carnivale, the OC and successful novel writers (such as Steven King and Orson Scott Card) are now regular contributors to comicbooks. To highlight four names from film working in comics; Buffy creator Joss Whedon is a writer on "Astonishing X-men", Bryan Singer is supposed to be writing a couple of issues of Ultimate X-Men, Babylon 5 Creator Joe Michael Straczynski is writing Amazing Spiderman, and Kevin Smith has written Spiderman, Green Arrow and Daredevil.
The influx of talent (particularly writing talent) has meant a general raising of the bar of accepted quality, and any dud books aren't allowed to just linger in the market (though this is also becuase the traditional comic book audience doesn't have the numbers to support all the books). The trade paperback market has meant that books are now written with this in mind - and storylines are much more akin to movies, moving in arcs or seasons, as opposed to meandering without any overall sense of direction. This in turn makes the stories (with a beginning, middle and end) much more suitable for film adaptation. Creators are regularly rotated on the titles that they're on, to push them for their best stories for a particular character. Both Marvel and DC seem to be polishing up their properties, particularly "icon" characters, with one eye on the big screen.
But in terms of developing new film franchises in the next few years, what are the prospects?
DC's "big 2" characters (Batman & Superman) have had their successful outings, and Wonder Woman is to follow. Though not quite in their league, she has had successful TV series in the past and with Buffy's Joss Whedon in control could do well. Beyond that DC's other big properties don't have such big name recognition, but under the right conditions it's other icons (Green Lantern, Green Arrow, Aquaman) or some of the lesser known books could do well. Catwoman didn't fail as a film because it was a lesser known character, but rather because it was a dud of a script, and diverted so far from the original concept that has endured for decades.
To me, DC's non-superhero lines seem better resources for film. Books of Magic could easily have been a huge franchise, though Harry Potter has gotten there first, maybe a film series will be made eventually if the market can cope with 2 four-eyed young magicians. Watchmen is a film that has been through development hell many times, and hopefully it will get off the ground sometime soon. V for Vendetta's success has made this much more likely. When it does get made it could be the film to redefine the clean cut superhero genre.
Many of DC's properties have worked well in the animated format, and I expect this to continue. The critically acclaimed graphic novel "The New Frontier" for example, looks to be adapted as a direct to DVD animated film, and could well be their best yet. Unlike DC, Marvel's animated ventures have been a lot more shoddy, and if their recent "Ultimate Avengers" cartoon is anything to go by, there isn't a lot of hope for their animated outings in the near future.
Marvel have somewhat sold off their family jewels already for their heavy hitting characters (X-Men, Spiderman, Hulk, Fantastic 4). The prospects for new film franchises seems a lot less certain. Ghost Rider doesn't hold any obvious appeal to me, though with strong marketing could well be a success. Ironman isn't so famous, but with a large budget could be a go-er. It also has a strong outreach to the fans, with myspace presence on the web, indicating that they will treat the property with respect.
Beyond that, there aren't obvious sure fire successes for Marvel - Captain America has previously looked a little ludicrous in a live action context, and Black Panther and Deathlok have struggled even in a comic book context, but this isn't to say there can't be hits. A comic adaptation can be a big film even if it's not a huge comic, just as long as the concept, script, budget and creative team fall into place. The most obvious example is Blade - never a particularly successful comic, but the idea works a little better in the medium of film.
Sin City, a massive success, was about as faithful an adaptation as one could possible get, taking the story, dialogue and even shot composition from the book. It showed that you don't necessarily need to make wholesale changes to a comic to adapt it to the big screen and also that a creator's involvement in the project can be a real asset, with original writer/ artist Frank Miller credited as co-director. Mike Mignola was a very involved in Hellboy. Mignola's book "The Amazing Screw On Head" has recently been made as an animated Pilot fro the Sci-Fi channel, and is about as faithful an adaptation of his illustrative style as I could imagine. I would expect this trend to continue - it was recently announced that John Cassaday would be following in Frank Miller's footsteps to direct "I Am Legion".
I think in the future we're going to see less new big superhero franchises, but there will continue to be films based on less well known comicbook properties (such as those mentioned in the last paragraph). In the vein of the Road to perdition, these could be films that you could watch and not even realise it's source is a comicbook - Walking Dead fit into the Zombie genre and "Buttonman" into the thriller genre.
I would imagine that these come from the the indie scene/ Vertigo books where the creator has much more of a voice. Indeed many of these creators look to be given a crack at writing the adaptations; Brian K Vaughn is writing the draft script for "Y: The Last Man" and "Ex-Machina", Brian Michael Bendis is scripting Torso (to be directed by Fight Club's David Fincher), and I believe Robert Kirkman's Invincible option includes him writing a script for it. Even in the indie world, Sam Keith's Ojo is being adapted into a film (albeit low budget).
We all have our favourite comic books and can't help but wonder how well they would translate. Off the top of my head I could see "Invincible", Watchmen, Bone, Y: The Last Man, Preacher, Black Hole, Powers, Astro City, Concrete, and Fables as being amongst the film properties that could make it big in the coming years (some of these already have film options). But this is for sure - whith hundreds of new comicbooks are being released every month, Hollywood has plenty to choose from for many years to come.