I think if you went into a game shop and saw Xenoblade chronicles X running on the wii u you'd have quite a shock if your perception of the wii u is of very low power. It's the first game that makes the wii u look technically impressive. I know there are games with attractive graphics but this actually looks quite respectable.
I think it will sell a few extra consoles but not a huge amount. Unless your a dedicated fan of Nintendo games there just isn't a wide range of exclusive software available on wii u to justify its purchase for most people.
Also we have moved into the phase where we are talking about the wii u's successor the NX and that is never a good time to buy unless there is serious discounting.