Does anyone think that Moana has enough popularity to eventually get an attraction at WDW?
I'm not sure popularity is the end all and be all. It's more theme requirements. A good example is Splash Mountain. Assuming planning started in the early/mid 80s for a late 80s open at DL, Song of the South hasn't been re-released by Disney since it's 40th anniversary in 1986 and, I'm willing to bet, will never, ever, be officially released again. So they themed and opened a ride, with an expected lifespan of decades, based on a movie that they probably suspected when planning will never again see the light of day. But it perfectly fit the FrontierLand theme, is beautifully told, is one of the best rides in the whole system as far as I'm concerned, and is insanely popular, regardless of the dwindling numbers of park goers who have ever seen the movie.
Frankly I'm amazed The Lion King does not have a ride. I love the show at AK as I think it's one of the best shows on property. It is one of the highest grossing animated movies of all time, an accessible classic, with follow along movies, merchandise, even a Disney Junior legacy series, and yet has a very limited park presence. Less is more perhaps or simply a lack of place to put it? With the show at AK, a ride might be double dipping and LK wouldn't really fit in MK except in AdventureLand.
I think Moana has some elements that fit the MK lands, but they aren't exactly needed. Would you put Moana in Adventureland? The Treehouse probably wouldn't be overly missed if it was swapped for something else, but that is an awkward footprint. I don't see her fitting in on the Fantasyland side, those are more classic fairy tale stories and I'd expect Tangled to be a better fit. The addition of SDMT indicates something about Disney wanting FantasyLand to at least focus on the classics, though you could make an argument Little Mermaid is a more modern tale than the rest.
WIR, Wall-E, and Big Hero Six fall within a few spots of Moana in gross these days as far as animated movies (WIR might be a stretch for that sentence). All of them have a better shot at becoming a ride or attraction in my opinion simply because they can fit into the theme areas that need the most updating, FutureWorld and TomorrowLand.
Moana at the Polynesian? Perhaps. Though the Poly already has a dinner show and I'm thinking she doesn't carry enough weight to be a significant character experience. Perhaps a Moana themed upcharge giant canoe fireworks cruise on the Seven Seas Lagoon?
Finally, DHS. I'm somewhat surprised there isn't a Great Movie Ride equivalent to a stroll through all of Disney's animated hits, with a focus on those under or not represented at the rest of WDW. I could see that concept not only working well, but easy to update and switch out as more movies are released. And it would push Disney's IP, clearly a strong push these days. Maybe that's what the suspected Mickey redo would focus on? I could see Moana level movies being a part of something like that, where it doesn't have to carry it's own attraction. But with all the announced work on DHS, I wouldn't hold my breath of anything else coming through there, unless Disney tires of paying whatever they pay Aerosmith and whoever owns the rights to TOT. And those don't seem the right options for this kind of experience.
Wow. That got longer than I thought. Maybe I should have stuck with a Magic 8 Ball response, "It is very unlikely."