Riviera is our favorite resort and we have 175 points direct and purchased another 125 resale in 2021...those were $152/point. We stay there each and every trip as part of a split stay and do own other points as well so we have the best of all worlds.
I think anything you are getting from $130 to $150 is a great deal for the resort. IMO, the reason you are seeing it sell for as high as it is is because people really do love the resort and are okay having points for limited to just there.
I would venture a guess that most resale buyers have other points, like me, to trade to other places when they want. None of us know if the average will stay as high as it is long term, and many of us, including myself, are surprised as we predicted it would be much lower when it was first announced. But, the resort sells itself and plenty of buyers out there who are willing to overlook the restrictions because they do want to stay there...of course, plenty who refused to buy because of them as well.
As you know, because they can only be used at RIV, be sure you are ready to commit to early booking, like 11 months, to ensure the best chance of getting what you want. Even now, SV rooms are really popular and go quickly.
In terms of the restrictions and a move away from them by DVD? It is certainly an option that they built into the contracts, but IMO, I would be surprised to see them move away from them long term.
As mentioned, there have been some that have been sold at a lower price point because DVD doesn't take resorts in active sales, so you very well could find a seller who needs to sell for less and in that case, it will be a steal!!!