I think that "platform exclusives" are a dying breed. One of the few reasons that I powered on my old PS2 was to play Grand Theft Auto: Vice City. Or maybe a round of Gauntlet: Dark Legacy with a few friends. Of course, as an Xbox Man, I enjoyed all of its exclusives such as Halo, Morrowind, and most recently Jade Empire.
But in the future? There will be much fewer. Most of the "exclusive" Xbox titles have been ported to the PC (no wonder given the similar architecture between an Xbox and a PC). But I'm also talking about crossovers between the Playstation series of consoles and the Xbox series of consoles. (go sit in the corner if you thought, "what about the Gamecube?")
Consider the economics of the situation. Game development costs are rising. Let's say you spend $5 million to produce a game. You get $4 million for selling it into each of the Xbox and PS markets. Net profit of $3 million. Sweet! But if you go exclusive, then you lose a million bucks. Of course, exclusive deals occur because the platform vendor pays the developer to make it that way. Let's say Microsoft pays the developer $2 million to be exclusive. Fine, they turn a profit of a million bucks. But they are still short of the multi-platform profit!
As game development costs continue to rise, game developers will have to go cross-platform to recoup those costs. As a corollary, it will cost the platform manufacturers more and more money to "buy off" the exclusivity, so they will be less inclined to do this over time (particularly for "first time out" titles that are unproven). That said, it is also possible to argue that the platform vendors will have more money overall, so they have more money to buy off developers. Possibly. But the idea is to turn a profit. If they sink their new-found profits into payoffs, then they really aren't ahead, now are they?
Take a look around. More games recently are multi-platform. With these new generation consoles and their huge capacity for visuals and artwork and animation capabilities, they are going to move dev costs through the roof. Just watch: next-gen games will tend to be cross-platform.
Goodbye, garage game developer.