Some critical things to keep in mind, which makes the new Poly building more unique than those other situations:
BRV... CCV later added. The addition of CCV did not add a significant number of guests. They mostly converted cash rooms to
DVC rooms. The cabins don't bring in a huge relative number of new guests. So usage of the pre-existing amenities did not change much.
Jambo/Kidani -- Kidani DID bring in a huge addition of guests. But they fully built our Kidani amenities, with its own feature pool, etc. With the massive size of AKL, while amenities are shared, the reality is few Kidani guests are going to venture out to the main AKL pool between it being so far, and they already have their own feature pool.
VGF -- Pure room conversion, it did not add to the number of guests using the resort.
So the question with Poly, is will they go towards the Jambo/Kidani model -- and FULLY build out new amenities with the new addition, including a new feature pool that would be equally appealing as the Volcano pool. Or will it be an appendage on the existing resort.. some new dining and amenities, but still heavily reliant on the old Poly amenities. (Not just pool, will it have it's own check-in and lobby (almost definitely yes), will it have it's own QS (some dining certainly, whether it will have a full QS, unknown), its own hot tub (I'm strongly suspecting yes), it's own sundry shop, it's own bus stop).