Can you explain a little bit more what you mean by you "think pokemon games can bring me back to good old times"? I think the Pokemon games have done a great job evolving into something so far removed from their original iteration, that they are their own league/category/type of game now and probably won't "bring you back to good old times".

Now, there are many, many great titles for the Switch that make up for the current lack of older titles that haven't been made available yet. But with the Game Boy and Game Boy Advance just hitting the Switch, I'm sure that will cover most of your bases eventually.

Just ask yourself if you really want to play Nintendo titles. If so, then yes, get a Switch. If you don't care one bit about Nintendo exclusives like mario or pokemon, you have other options. But I will say, the Switch opened me up to so many more titles without having to do any research on what was already available on other consoles, cause I was getting a Switch either way, and if it became available to the Switch physically, then I knew I'd at least give it a shot because it was going to end up in my library eventually. And the first game I fell in love with was Mario+Rabbids Kingdom Battle, which I wouldn't have been able to play anywhere else. Then the second game I fell in love with was Octopath Traveler (what can I say, I am a simple man), which at the time was only on the Switch as well, and sure brought back that snes nostalgia. Not to say there aren't other games out there on other consoles, I know now, that are comparable in quality, if not better. But the Switch and Nintendo in general have always been a prize fighter even when standing toe to toe against other heavy hitters.

Performance wise, I had no complaints with The Outer Worlds or the Bioshock Trilogy. The 64 games are also a blast to play with a Nintendo Online subscription. But I also play a lot of Wheel of Fortune, Monopoly, Family Feud, and Who Wants to Be a Millionaire, where performance isn't a huge deal. And I don't play many shooters, though I would say if it's not on the Switch, then it is probably a performance issue. If you need to play a lot of games on day 1, then expect performance issues. Game Freak has been busting out Pokemon games at the speed of light and quality has definitely suffered. Except the remakes have been superb imo. All in all though, I would say performance across the board is indeed "acceptable". There's maybe only a couple of titles out there that are unplayable but are so obscure you'd probably never come across them.

Last but not least, feel free to speculate on the next system news. But nothing has been announced yet. Though Nintendo system life cycles are around 7 or 8 years, so maybe not much longer now. I kind of always thought they might keep the Switch as their staple focus for much longer than previous consoles, but that's just me and please don't downvote this post just because of that. I too, would like newer and better, and it would be preferable for the public to know what Nintendo plans on doing, but then this isn't exactly realistic in terms of business and technology.

I would say getting a Switch now is definitely worth it now more than 6 years ago, as you have an incredible amount of games to chose from and you can pretty much start anywhere, play anywhere, and play with any one. They've also made updates that added bluetooth functionality and more. You know it will be around for a long time to come.

tldr; yes. yes. yes. no.

Yes there's loads of fun games on the switch

Yes, there's so much stuff on switch, anything that can be considered anime style is less than 50% in quantity

You will buy one, play it for a week constantly, then not touch it again for another year or so, then play for a week and repeat

Look at the Steam Deck. The Switch is ace and there's some lovely RPGs (Disco Elysium is ace etc.) But a Deck might suit you better? I've been running Skyrim on it and it's a dream. Highly recommend both TBH!