for gamers? no
for sales? probably. but again it depends, the people that bought the wii arn't gamers, so the market share might not want to upgrade.
if your a 50 year old playing with your grand daughter in bowling you won't need or want a wii u. nintendo showed a graph of who bought or wanted their console.
5-13 year olds and 40+ year olds were the gist of the sales.
So, the older folk probably won't want or care about the wii-u, the younger guys might want to upgrade but maybe they won't want the wii-u, depends on a lot of stuff for them