First, to answer your question in the thread's title, the wii's lifespan will be five years as the first nintendo console. Nintendo will then release a new one an wii will probably keep selling for one or two other years. this will happen no matter what, because nintendo makes profit of the wii, even if it won't win this console generation.
Second, after two or maybe three years a console is either a winner or a loser console. After that amount of time, third parties will definitely decide which console they are supporting. Some people say that nintendo consoles stop selling after three years. This is true for n64 and gc, but not because they are nintendo consoles but because they were loser consoles. This is important because a lot of sony fans state that the ps3's sales will increase after some years. This won't happen. Start selling slow and increase sales later only works with a head start, but if a console already starts with handicap, it needs strong sales right from the beginning to at least have a chance to catch up.
Third, hd will never become important in this generation. One reason for that is my second point, because at the moment hd is spread widely enough, the war of this generation is already over and the winner is clear. the other reason is that people who have a hd-tv are not going to buy a hd-console just because they got such a tv. this is the mistake many of you make. I, for example, own a hd-tv. but the question which console I am going to buy is a different one and does not depend on the tv i own. it would matter if the wii wouldn't work with a hd-tv, but this is not the case.
Fourth, and last, the statement xbox and ps2 owners are not going to buy a wii is just ridiculous. I guess they were the strongest buyers of wii's until now. many of you believe that all the ps2 owners are hardcore gamers. this is not true. i guess that 80 percent of the ps2 owners and 50 percent of the gc and xbox owners are not hardcore gamers. they are not just casuals, but they are gamers who own around 10 games and probably didn't finish them. This people are now buying a wii. They are interested in consoles, but not in the way hardcore gamers are. But they already know how to handle a console which makes them fast buyers of wiis.
