I am not sure how those resorts opening (in case of the
Disneyland dvc, I am quite sure that is still a big if) makes the impact on resale less. If anything, is just two more resorts you cannot stay at if you buy Riviera resale, which should depress the prices if they are great resorts. I generally wouldn't think the disneyland dvc has much of an effect either way.
To me the restrictions will be impacting resale to an unknown extent for 20+ years, or until the 2042 resorts are being resold etc. Before I continue my diatribe, I will preface everything I say by letting you know that literally no one listens to me so perhaps that says something about me moreso than everyone else who came on disboards, posted that they loved Riv but really weren't sure with the restrictions etc., and then bought anyway two days later. There are literally five threads exactly like this, and each time the person was, at least to me, pretty clearly looking for people to push them to buy. Which some did. Then they bought and that was that.
One positive thing is that, if you were going to buy direct, it is the only resort that makes any sense at all to me (and Disney has orchestrated that obviously). I would maybe wait to see a little more on whether the restrictions really hurt resale or not; I am not totally sure what the impact will be. Keep in mind, the intention of disney is to drastically reduce the value, so one way or another, they will continue to try and do that, even if the restrictions are not successful (do you want to own a product for 50 years run by such an entity?).
At the end of the day, whether to buy really depends how you view DVC. I view it as a way to save some money, given the fact that I will be going to disney at least 7-10 nights a year, or perhaps 5 out of six years, for the next 15-25 years in deluxe hotels (Disney deluxe) in a one or two bedroom. I already have the direct benefits so perhaps the situation does not match yours but, again, these 'benefits' are literally meaningless from a $ standpoint unless you are going twice a year for more than 6 days each time. In that case, at Riviera, you would probably need over 220 or more points a year, which will run you double what a contract at SSR would plus $2/pt/ in fees a year etc.- I understand Riv is a lot nicer, but there is no value in buying. Put another way, there is no difference, at least for the next 20 years, in just paying cash/renting points and having no obligations whatsoever to go; just don't undervalue that freedom. If you spent $15 grand on a membership then decided it wasn't for you after ten years and sold for a bit less than what you paid, you saved money on your vacations and got out ahead. If you spend $30k and can't easily sell without taking an absolute bath, you have now paid 3x what you otherwise would have and had 10x the headache, oh and you will definitely feel pressure to go every single year (depending on how many points you buy of course).
I would just be careful and really think about it before doing it. Those who argue they are buying it for their kids should also never use that as an excuse to overpay; kids don't like disney, kids get divorced, kids don't have money to pay, parents get divorced etc. I was happy my dad bought DVC, however if he would have invested the difference between buying RIV and SSR as in my example above, well let's just say I would rather have the $100,000+ and the SSR contract.
To me, Riviera does not fit into what I want DVC for, and you summed up the reasons. I am just not going to pay now for the promise to save money in years 22-? (assuming I even live that long) and I personally cannot understand why anyone would ever do that. When you add the restrictions that could crush resale value, I'd rather buy a 2042 resort and know exactly what I am getting and how much money I am saving or not, so I can make an informed decision. Until then I'd pay cash, rent points and sleep around a bit to see what you really like. It won't sell out in the next year so you have some time.
Good luck.
