As somebody who played Skylanders (Giants), I have to say that it's actually a fun game. Greatest game ever? No way. But fun. When you weren't being frustrated trying to get your hands on those last three figures you need for your collection, that is. (In the end, I got every character that was released in generation 1 or 2 of the game, but just one copy of each guy.)
I think they're running into the same issue that the Guitar Hero/Rock Band genre did. So much hardware, and every game/generation has to add its own into the mix. Pokemon Rumble, Disney Infinity, Skylanders 1, 2, 3 (and I've seen trailers for the next entry in that series already)... There's just not enough room at anyone's house or wallet to hold them all. I think this is a genre that's going to burn out soon.
That said, one of the things that helped Skylanders succeed was that the figures are high-quality and have designs cool enough that you don't get depressed every time you see them. Nintendo will, I assume, also succeed in this area. And they've got one advantage over Skylanders: they'd be building a game with established characters that players love and will want to have. They'd just better not pull the Disney Infinity crap with the blind grab bags of tokens. I don't like that game's general design, either, where you can only play with characters in their own world or in the sandbox where you have to build your own game.
So if anyone can make it work, it's Nintendo. But I won't be buying it, or a Wii U just so I could play it.
And yeah, a Fallout 4 announcement would make my month.