I actually fear, that we will not see the rise "mature games" in the way you define it. Maybe in a hundred years or so, but we won't see it. Games in general have a far too bad standing in our Society. They are only accepted, when they ar sport, or you play for money, like Poker. Board Games … although many people like them … are still a Fun for Geeks. Although more people have PCs and Consoles at than they have Boardgames, Computer- and Video-Games still will never leave the realm of "immature", "casual" and "meaningless", not matter how much sex or gore is in there.

Actually I think, the term "Casual Gaming" is misleading. There are no Games, which aren't casual Games.