No, but most of these peoples will not really be interested in more or less classic hardcore games. They will be more interested in mini games, that are fun to play with other people. When they have two or three games, because for them the games do not really matter, but the fun that they have with other people. For Nintendo this is quite fine, because they already earn money with the console itself and they already have several mini games collections. For third party developers these people are probably dead numbers, the same problem that the PS-3 has with people that said "Oh fine a cheap BluRay player". Most of these buyers won't start to get deep into games.
So those who today spend money on the Wii will just give it up? Well mayby but I doubt it.
For the total sales of the hardware and software Wii can live on getting the "I just buy 2-3 games people". Honestly I think as long as 3rd parties and Nintendo continue delivers titles to Wii I have a hard time to see people just leave for xbox360 or PS3. I mean I can see a lot of people buy tiger woods, fight night, virua tennis after playing Wii Sport if these games will come to Wii. Some games will always be better with a traditional gamepad, but so what?
To state that 3rd party sales will drop like a stone in two years because of the crappy graphics make me wonder. Because there is some genres that might get some new energy because of the Wii controls, I personally wants a more in dept boxing game for Wii.
I also think that you underestimate the casual and "non-gamer" crowd. At least in Japan the DS is selling sick amount of software for the moment, if the DS can do this I think we might find that Wii can do the same thing if the entry and game cost can be kept low.
NOW NOTE: I have all the time stated that what might
happen, what I am saying is not the truth or the only future. But honestly I think that combining the casual gamers and N-fans will keep the 3rd party sales a float. More 3rd party exclusive might also draw in other gamers (more so if the Wii gets really cheap during the next two years) and keep the exclusives coming. If you look at the latest chart, from USA, the two best selling 3rd party games is exclusive, so a big treat against the sales for the 3rd parties can't as far as I see not be seen.
Actuly I think the strength of the Wii is that it didn't try to outperform xbox360 and PS3. It tries to be something different. Not only is it different but will most probarbly continue to be the cheapest consol on the market leading to that it can also be the second consol in many housholds.