A fun game is a fun game, no matter how you look at it!. There are countless examples of this ... Tetris, Pac-Man, Geometry Wars, Wii Sports. Fundamentally, both audiences look for the same things: accessible fun that turns into engaging depth over time, something that feels rewarding for the time invested. In another domain, all Pixar movies could be classified as for kids, but they're layered with superior technical execution, adult innuendo and cinematic excellence. They succeed in creating entertainment that satisfies almost every demographic, and there's no reason games can't do this, too.
"A well-designed casual game appeals to everyone," says PopCap's Gwertzman. "What it doesn't have are needlessly complex controls or user manuals that are dozens of pages long. Since I entered the casual game space, I've become appalled at games that think it's OK to ask the player to master a dozen types of key combinations in the first 20 minutes. I think that's the product of poor design! It's almost always possible to simplify the UI and make the game appeal to a wider audience."
PC gaming isn't going to explode thanks to lots of people suddenly becoming hardcore. The casual market segment is already much larger numerically, and despite this, it also possesses far greater potential for growth. It's also catching up quickly in dollar value. When we combine these factors, it's basically impossible to create a plausible scenario in which hardcore gamers represent the future of PC gaming. Like it or not, that mantle is worn by Uncle Charley, Aunt Emma and the hundreds of millions like them who own PCs but will never be mistaken for hardcore gamers.
At present, many companies are working to attract substantially larger and broader audiences through a varied spectrum of initiatives.