I'm sure a Rapunzel stage adaptation will happen eventually. Maybe they'll actually call it Rapunzel, too, since they've learned from the TV series that "Tangled" is not a memorable brand name, whereas everyone knows Rapunzel.
I expect there will be a
Moana musical eventually, too. It's a shame
Mulan and TP&TF will likely never get them, considering
Hunchback got one and now it looks like
Hercules may get one as well. I mean,
Pocahontas deserved one, too, but Disney is probably walking a tightrope with that property in this day and age. Unfortunately a TP&TF musical would mean bringing Newman back.
I'd rather they got Menken to create any additional songs for a hypothetical musical; I still hope maybe he'll make music for
Tiana or the
Wrecked Princess series so eventually Tiana will have the Menken song she deserves and was denied by Lasseter.