With the sluggish sales of the Wii in Japan since about 12 weeks and the recent disappointment of first week sales for Super Mario Galaxy I am starting to doubt the longevity of the system. The Wii might be a fad after all which wouldn't be that surprising considering the sales of previous Nintendo consoles like the Gamecube, which started well at first too. Although the sales of the GC dropped much quicker.
I think the reason why the Wii could maintain its strong sales longer than the Gamecube is because the Wii had Wii Sports. I am worried what will happen to the western market once people get bored of this game, my guess is that the sales of the Wii will take a serious hit. Most of the Wii's success can be attributed to party games which is evidenced by the sales of Wii Play and Mario Party 8. This can't last forever.
I also lost faith in Nintendo as a developer of top notch first party software after the disapointments their combo of big games (Zelda, Metroid, Mario) has been. Zelda had tacked on controls, Metroid was a streamlined 5 hour game (if you want to see a picture for proof, let's exchange Wii numbers) and not the deep experience I was used to from the Gamecube games, Mario seems to be a totally easy game now (thanks to the casual gamers who can't handle hard games) which can be finished in about 7 hours. I feel betrayed by Nintendo and I am sure that I am not alone, many other longtime Nintendo fans probably feel the same way. Easy games suited for casual gamers is not the way this industry should heading to, I want to play my deep singleplayer games like they used to be. Instead of making games for me, Nintendo develops Wii Fit and other crap which aren't even real games.
Because third parties still don't see the Wii as viable platform we will get mostly minigames from them, which make up already the biggest part of the Wii's library. The strong sales of the Wii early on didn't matter as all the major third party franchises I care for are still not in the works for the Wii, only for 360/PS3. That's not what I would call serious support. I can't really blame them, seeing that only Nintendo games seem to sell well on Nintendo systems, the Wii is no exception.
I think once the 360 and PS3 get another price cut, the Wii is finished, because I don't see Nintendo dropping their price as well, they will continue to overcharge for their outdated hardware which as we all know is only two Gamecubes duct taped together.
Now another reason why I could see the Wii failing is the growing adoption rate of HDTVs. Even the PS3 will be able to easily pass the Wii because thanks to the Cell and Bluray it is futureproof and will last for at least ten years. On top of that the 2008 lineup of the 360 (Fable 2, Halo Wars, Banjo 3) and the PS3 (MGS4, GT5, GTA IV) can't be countered by anything the Wii offers.
Generally the Wii sold well until now because it is cheap. The old technique used in the Wii can't last forever and we will most likely see a Wii HD in 2009, just like Pachter said.
Other problems I have with the Wii are: Games for it so far haven't proven that the Wiimote can be used in more than just gimmicky ways. Nintendo doesn't seem to care for online, most games don't support it and in the ones that do, I have to deal with the annoying friend codes. The virtual console seemed to be a great idea at first, but let's be honest, the games are overpriced. I mean €8 for a Megadrive game, seriously?