They won’t have a problem selling them at all just that they will go for around 50% of direct. There will be a market for people who just want to stay at the new resort that will not care they cannot use the other
DVC resorts. I myself would consider buying points there resale for the right price. Plus not many people go into a purchase like this thinking about selling, they are too caught up in the moment.
I'm not so sure, about what the resale value of Riviera will be. Obviously, if the price is low enough, and if people are perfectly content to just stay there, then purchasing a Riviera resale contract makes perfect sense. BUT, if there are bunches of other resale contracts available, for Legacy 14 resorts, and if the price is similar, won't people tend to gravitate to the L 14 contracts? Of course, that will then mean that the Riviera resales continue, but at an even lower price. Also, by this standard, having Riviera, Reflections, and similar future DVC Resorts be so limited after Resale, they will actually be INCREASING the relative value and desirability of the L 14 resales. So the more 'Riviera' they sell, the more your current contracts might actually be worth.
On another note, I have heard that the average DVC owner keeps their contract for 10 to 15 years. Don't know how true that is, but it makes sense. People get older. They grow tired of Disney and they look for new vacation experiences. Then they want to get out from under the Maintenance Fees. So they sell.
Disney might decide they made a mistake by selling 50 year contracts. Why did they choose 50 years? Because that is kind of a Timeshare standard. But now that DVC is established, they don't need to continue with 50 years. I don't see why Disney might not start selling contracts that only last 20 years or 25 years, in the future. They could probably get pretty close to the same price, and the resale market would shrink considerably. Of course, if they switched over to a strategy like this, while the L 14 resorts are also still out there, then they would have to go against the L 14 Resale market! But if Disney successfully navigated that, then they could expect to get TWICE AS MUCH from Riviera over the next 50 years, since they will be able to sell it twice, once now, and then again in 25 years.