I'd say it's more likely they'd just port Color Splash. Especially given how recent the latest entry is and how close we are to the launch of Switch. I'd love to see a more classic Paper Mario but that just doesn't seem to be in the cards anytime soon.
Though I am intrigued in seeing what they do with the Mario and Luigi series on Switch.
I don't think we'll see a return to the classic paper mario rpgs. It looks like the Mario and Luigi games have taken over that role completely. PM:TTYD will be close to 13 years old when the Switch launches.
The Paper Mario games were never bad to begin with, and I'm fine with the change of the series. Yes, SPM, SS, and CS were different, but they didn't "killed" the series.
There's been a Paper Mario game every generation since PM64. If the Switch is truly Nintendo's answer for both home and portable console, then devs are likely to have the time to make at least one.