I really like FPS' on the Wii though I wouldn't say the Wii will dominate that genre. It's already divided between the mouse/keyboard crowd and the dual analog crowd so the Wiimote crowd will just be a new and viable subset. The Wii should have no trouble with any sports game that mainly involves one player at a time (hard to explain what I mean but bowling, golf, fishing, baseball to an extent, etc.). Football is already shown to be somewhat better but along with basketball, soccer, and hockey I don't think the benefits of the Wiimote will be enough to make it a genre dominating console.
Arcade style racing, flight sims, and shootem up games should be easily dominated by the Wii though I think realistic racing and flight games will be more represented across the platforms. RTS, simulation, and strategy games will probably just about only be seen on the Wii though they aren't major genres for consoles. I think RPG's will be owned by the Wii but not because of the Wiimote. They would be focused more on the Wii's lower cost, greater install base (primarily in Japan), and DS connectivity.
I agree the main inhibitor for the Wii is the lack of buttons though I don't know how much of a problem that will really be. Several games have already reliably mapped functions to motion controls. Actions like opening doors, reloading, kneeling/standing up don't require a button.
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