We stayed at the Poly last year and I have to say it is my favorite resort. I would hate to see them tear down this resort and build new. The longhouse format has a certain charm to the place that you don't get with the mega-resort of some of the other hotels. I believe that a complete tear down of the resort would make the room sizes smaller (the Poly has some of the largest average rooms at WDW) and put more of an emphasis on DVC. Maybe a complete renovation of the GCH (with a possible teardown and rebuild) is in order. I believe the Rapa Nui has a lobby area that could be turned into a temporary check-in area and isn't there a banquet hall onsite that could serve as a restaurant if there is a complete GCH renovation? As far as a hot tub, I wouldn't need that. You know what they say about hot tubs--human soup!
Although, here is an idea. They can teardown and rebuild the GCH with all the newest amenities. And as part of the rebuild, they can add a few floors on top for DVC or Concierge type rooms, some of which could have awesome view of the castle. At the same time, they could leave the longhouses alone, except for a remodel of the rooms. You keep part of the old (the longhouses) while introducing some new (a new GCH).
Although, here is an idea. They can teardown and rebuild the GCH with all the newest amenities. And as part of the rebuild, they can add a few floors on top for DVC or Concierge type rooms, some of which could have awesome view of the castle. At the same time, they could leave the longhouses alone, except for a remodel of the rooms. You keep part of the old (the longhouses) while introducing some new (a new GCH).