The Wii has loads of gems on it that don't get much attention. It's an interesting console to collect for because there's actually a very large variety of games, many of them being much better in quality than they would appear to be. I hate motion controls, so even after I bought my Wii I didn't pay much attention to collecting for it, but it's now one of the biggest parts of my collection.
The Wii U is off to an incredibly slow start, but I think that in time it's going to be the same way. It certainly isn't a failure yet, especially considering how many successful consoles of late have had slow starts. The Wii U's been worse as far as that goes, but I'm guessing the trend will continue in similar fashion with the PS4 and X1. They'll sell better, of course, because they have the AAA games and dudebros behind it, but the sales will likely be much lower than anticipated. And in that regard, many developers with the mantra of "throw money at it to make it better" are in for a rude awakening coming up.
Also, the notion of Nintendo of going software only is pretty silly. The 3DS has been selling incredibly, with momentum steadily increasing. The Wii U could end up being a total bust and Nintendo will still be raking in the money. They might go handheld only, but that still seems unlikely. In any situation, though, they aren't going anywhere for a long time.