Considering how few fitness games there've been this generation (not rythm games, games focused only on fitness), this seems like the biggest there's going to be before PS5/XBoxTwo. The genre has fallen quite a lot since the Wii days, so that's not that farfetched. There is little to no competition this days...

How could it not?

I think it'll be the most successful of them for this gen (not that hard to achieve) but I don't see it being anywhere close to what Wii Fit achieved.

I think it'll sell a couple million LT, but won't get anywhere near the crazy heights Wii Fit reached.

I don't see the crazy huge sales that Wii Fit had. Ring Fit is an RPG with a Fitness Element, not a raw fitness tool like Wii Fit is. Not everyone likes RPGs, giving Ring Fit more limited appeal right away. That said, I still think it'll sell well. 2-3 million copies worldwide by mid-2020 is my guess.

Theyre gonna bundle it up with the console so it'll end up selling something between 3 units and 3 billion.

Considering it's gonna become the only selling fitness game on console I'd say yes.

That would be a pretty bold prediction that I'm quite hesitant to make, but I can see it doing like 5-7 million. Great but not Wii Fit phenomenon level. Its greater depth will limit its appeal somewhat (though it certainly looks more fun to ME than Wii Fit..)

A Nintendo game, albeit a minor one, versus.... well, what else is there exactly?

That’s not saying much to be fair.