Yeah, I was kind of "meh" about TTYD, because it just felt less fresh than Paper Mario, so I can see how that would work exactly the same with one going from TTYD back to the first one. I'm glad either way that SPM decided to shake up the gameplay.
I'd really like to see a SMRPG2 that's co-developed by SqEnix and Nintendo, finding some kind of middle ground between the different series. I don't think the modern Square lives up to the 90s square, but they do still know a thing or two about... cinematic presentation? So they could still turn the Mario World on its side in an interesting way. And Nintendo could make sure the game is actually fun to play.