It is true that in terms of supply, the supply i now finite. However, this was already the case for many sold out resorts anyway, so nothing changes there. This will only affect the newer resorts.
On the demand side however, there is an ofsetting effect in terms on a possible drop in demand. Many resale buyers are people who attended a Marriott presentation, liked the concept, but discovered the resale market before they bought developer. But now, people will attend a points presentation and will find out they can only get resale deeded weeks on the resale market. Whether they buy those or just forget about Marriott is still unknown... on one hand a resale week for $5K-$15K is much better than $50K for points. On the other hand, a deeded week is not "the dream"...
On top of that, at some point you will have resale points. There will probably be a higher demand for those over deeded weeks giventhe "flexibility". Depending on where the price for resale point settles, and the penalties imposed by Marriott on resale points, deeded weeks prices could crash at that point. This is a grim picture, but imagine you could get resale points at $2.5/point... (assuming a 75% drop, like many Platinum weeks) - would you buy a deeded week then? On the other hand, if the price settled at $5/point or more, I think deeded week prices could remain relatively stable. Either way, I don't see them going up because of the effects I just mentioned, which will only get worse with time.