The counter to that, is that Miiverse also contains some of the most amazing looking sketch art I've ever seen. Some seriously great stuff to be found on there.

Also, while a lot of comments might be random, in my experience quite a lot of it is related to the game "community" they're posting in, and often actual dialogues with people helping each other through games, etc., does happen. It's worth that much at least. Not to say it can't get better, it can, but it's a neat feature.

Probably not. They show trailers of Wii U games on the 3DS Eshop, and that hasn't helped much.

It might. But it depends on what Nintendo is able to bring to the wiiU. 3Ds gamers will get interested if the wiiU game is interesting enough.