This wouldn't work. What about the owner who bought a 25 point contract a year ago, and doesn't sell. Just keeps it for the next 30 years, and getting all the perks and discounts that go with it, yet racking up the administrative costs that his dues don't cover.
As for buying back, what happens when the public learns that Disney is buying back all smaller contracts such as 25 point ones via ROFR. Does the seller get a friend to offer them $200/point, knowing Disney will then have to pay that amount? Disney won't, so any contracts offered above a certain threshold sale amount still won't be ROTF'd by Disney.
I know our Marriott is like you said, those who buy direct from Marriott, and those who don't. But a lot of that is because of the extremely large price difference between buying direct or buying resale. Disney on the other hand, via ROFR, is keeping resale prices fairly close to Disney prices. I can buy Marriott resale for less than half the cost of direct. No one is going to get
DVC for half the cost of direct. So in this case, if someone bought 300 points resale, qualify them at 'gold' status and they get the perks.
Treat it more like the airlines, or car rental agencies. They have different levels. Disney could simply have two levels, perks or no perks. Simple enough.