Whatever Happened to the Wii?

I'm not a gamer. When I was younger, I used to play computer games: racing, usually with my brother, or that hilarious Spider-Man one based on the first Tobey Maguire movie, or Harry Potter, up until I got to the spiders in Chamber of Secrets and freaked out. But then, about ten  years ago, we got a Wii. 

Do you remember the hype surrounding the Wii? It was EVERYWHERE, and people raved about it. We used ours mostly for "exercise" - Wii Fit, or Zumba (man, those songs get stuck in my head for DAYS), or Just Dance (don't try to tell me rocking out to a censored version of Katy Perry's "California Gurls" doesn't count as exercise). 

Later, I had a fantastic Adventure Time quest game, but since I barely have time to sleep, much less play games, I've sadly had to abandon it. The last time I played, I was defeated by Death and had to restart the level...which was pretty fitting, actually. 

My sister and I are planning on using it for exercise again. As of this writing, we're debating whether we want to Zumba or Just Dance first, so by the time this is published, it's entirely possible we haven't even touched the console yet. 

But, personal experiences aside, my questions are thus: whatever happened to the Wii? I rarely see commercials for it anymore, and I don't think I know anyone who still has theirs (and if they do, I don't think they use it). What's the current big gaming console that everyone's into right now? Is Wii technology considered "old" (it has been a decade)? 

And can someone please tell me why the batteries run out every time I even consider playing Guitar Hero??