I'm not so sure.
Ignoring HHI and Vero for the moment, the first to expire will be BWV, BCV and VWL in January 2042. Those are arguably the most in-demand resorts available. Assuming that Disney intends to keep those resorts in-operation for another 50 years without any substantial changes, they could start marketing "new" 50-year contracts around 2040 or 2041. The first people to get the offer will be the current owners. Those who don't renew will see their points offered to the general public.
The millions of points re-acquired won't sell instantly, but there will be substantial demand. And DVC will be selling with little-to-no up front investment since the resorts already exist.
Next up would be Saratoga Springs, but not for another 12 years. Given the general perception about that resort, I would say it's a fair candidate for some sort of re-development. I'm not sure that it would be worthwhile to try and resell the 12 million or so points without some modifications to the property.
Then you've got OKW and AKV in 2057, BLT and VGC in 2060, and so on.
In other words, Disney's re-acquisition of the resorts is staggered in such a way as to aid the re-selling process down the road. Re-acquiring the points is a gradual process, and really it's not much different than building a brand new 300-400 unit resort in the first place.