godspeeed: I strongly doubt it, PC gaming has always excluded Mac computers so I dont see them adding tablets to it.
MobiusArcher: I didn't mean to add them too the PC sales. I meant put them up against it.
If two architectures are clearly competing with popularity, then it makes sense to put them against each other. Mac computers would clearly qualify, but are they eating PC game sales? I have no idea how many games Mac gets annually anyway, I know some PC games get Mac versions as well. Ever since Marathon games, I don't recall publishers opting to release a game for Mac but not PC, while many still may opt to release a game to e.g. a PC and not consoles, at least initially.
Tablet and smartphone games probably compete the most with handheld consoles, not PC (nor "big" console) games. Nintendo has already complained how the cheap games for smartphones are eating up their handheld console market. People play more and more on their Iphones instead of their Nintendo DS.
As for comparing consoles vs PC... I think it is a bit unfair to compare the sales of PC games (which is one platform to release games for) to all consoles combined, which are several platforms. Most people don't own all three consoles (XBox360, PS3 and Wii), but only one of them. Success of e.g. a PS3 game does not guarantee success for Wii games, for example.
That said, I feel PC and console gaming are, and always have, been somewhat different experiences. They are not exactly the same, simply because most consoles are in the living room, while PCs are not. While there is certainly lots of overlapping, the different setup and controls favour completely different genres. Party games, offline multiplayer games (e.g. sports and beat'em ups), and "interactive movies" are clearly much better suited for the living room in the big screen, while for a deep strategy game or RPG most would probably rather play it in peace so that they can concentrate on it. PC gaming is a more personal experience, for games to be played alone.
Hence, even the same person might play both on consoles and PC, but completely different games. Single people living alone don't necessarily have to make such choices, of course. Or, then you have to limit your "deep" gaming time to when all others are sleeping, and use only headphones in the living room. :)