Ubisoft and Bethesda to make the ultimate sandbox RPG with free-running and stealth aspects, crossing Prince of Persia with Oblivion. Completely customizable characters, so you can start out as a straight solider, going gun-ho, then decide half-way through to start maxing out in spells. And if you don't keep up certain skills they fade, so as you go more and more mage, your solidering skills slowly degrade depending on how much time you still spend using them. Also it would be a real moral choice game, none of the simplified crap thats going on now, so that there are some choices everyone will hate you for (killing babies), and some everyone will love you (saving babies), and then a lot will have different groups hating you while others love you (helping a woman have an rape-baby abortion).
Then make it into an engine that you can place any timeframe/story over the top of, so a modern gun-toting game and fantasy rpg will both be based off the same engine.
After all this release a dozen games covering every possible market for the engine, then sit back and watch the money rolls in from buying my most awesome of games.