The reason Disney is likely 'tripping over' itself to make Aulani authentic is because it's actually located in Hawaii. Hawaiians will work there, see and form opinions about it, etc. Even if Hawaiians are not the primary audience, there is still great value in making an authentic product that is more pleasing to them.
Likewise, guests to Hawaii are, in general, probably more astute as to Hawaiian culture than are guests to Walt Disney World. Thus, there is more demand there for the authentic experience rather than the idealized or sanitized one. While there is only one Fantasyland-proper at WDW, isn't it all a fantasyland, to a certain degree?
Beyond that aspect of the rumor, I really don't see anything happening to the Poly. It's just too popular to justify shutting down large portions of it at a time. Now, I could see shutting down two buildings if it meant replacing them with a much larger DVC structure that would quickly recoup the lost revenue. A shutdown due to asbestos or a simple retheming? No way.
Personally, I think it's about time Disney finally dusts off some of the plans for the unbuilt properties on the Seven Seas Lagoon. In my mind, this is the best real estate on which to expand as there is demand for these resorts. Stop building plain properties out in no-man's land that really have no special allure (I'm looking at you, Saratoga Springs), and focus on properties that will have greater demand (kudos on Art of Animation). Given their proximity to the Magic Kingdom, anything on the SSL automatically has at least one advantage. Add a nice theme, and you've got two selling points. DVC and resort expansion should be means to fund substantive attraction expansion in the parks, so I see any objections on those grounds unpersuasive. I also think that more resorts on the SSL would look better (after all, you don't see people complaining that there are two many World Showcase pavilions at Epcot), not worse, as some have contended.