Overall I don't think there's enough track record or information to truly know what they'll do, however, I do think there's plenty of time to do an extension of any type now and for some methods, it wouldn't require much or any advanced warning. The only historical info we have related to DVC is the build out at BWV & OKW and the THV. I don't think AKV would apply The BWV & OKW projects were so small and included within the framework of the current resort, there really wasn't any choice but to include it within the resort proper. The THV didn't have the RTU expiration issue or the sales potential for what's being discussed now but, IMO, it clearly should have been separate.
I'll also point out what should be obvious, that if it's separate, it'll be separate from a reservations standpoint as well meaning that current VWL members would only be able to reserve at 7 months out. For VWL I think including it within the single resort would be better, they just have to work out the other details accordingly so they can charge $165 a point rather than $125 a point and possibly they can find a way to get some income on an extension as well. Possibly they can work it out to have some expiring at a different end date though I'm not sure how.
I'm not seeing how they can take what Marriott did with their trust conversion and adapt it here. What Marriott did was to create a new system completely and then create a crossover option. To do that it'd have to be a new DVC II, not just a separate resort as I read it. If that was the direction they wanted to go, it should have started with VGF or even BLT.