20-Year Prospect
Since the ancient Greeks first developed the art of campfire stories into what they called drama (or δράμα, which is pronounced "drama"), tales of the human experience have been brought to life by actors. So yeah, humans have been pretending to be people they're not for thousands of years (at least), so we think it's safe to say this career will be around for another twenty.
In fact, today's actors are finding all sorts of new places to strut their stuff, thanks to the interwebs, camera phones, and the rise of social media. Who needs to fight for work as an extra on a third-rate TV show when you can become a sensation on YouTube? Who has to audition for movie after movie after movie when you and your pals can write and produce your own version of Pride and Prejudice?
Then there's the career itself. Gone are the days of black and white, hand-held headshots. Now everything is in color, online, and kind of small (especially on a tablet). In about twenty years, casting directors will probably just say your name and a 3D version of your demo reel will start up on the kitchen counter.
Of course, even with so many new places to expose yourself, there's no guarantee you'll ever become a famous actor.
Don't worry; even if millions of dollars and fetching Prada footwear are never yours, there will always be dinner theater. People gotta eat, and if they can solve a murder or watch two knights battle at the same time, even better.