1. Do enough Poser users exist to support the need for another site/marketplace to take over for RDNA on the Poser side, since RDNA is seemingly phasing out their support of Poser with this merger?

Think there is enough Poser users. But I think you should try to ask yourself the same question a bit differently. Is it possible to make a new marketplace which can compete with the current ones? If you follow in the path or simply copy the already existing places there is most likely not. But if you can make a place which improve on the things that current users are not happy about with the current ones, will you have a chance?

2. Is this community ready for an entirely different approach to managing figure creation that could solve Poser’s need for a truly modern figure pair?

Not really sure what you mean by this, or at least i think it will be difficult to give you any good feedback with so few details. If you refer to if Poser is ready for new figures? I would say yes, I think for people making figures with the intend of competing with the current ones like V4, M4, Genesis etc. have a hard time, but if they could convince vendors or content creators to make stuff for them, they could have a very good chance of being popular. A way to do this or at least consider could be to offer this figure free of charge to the content creators and vendors, and if its a good model there is a chance they will start making content for it and therefore do the job or help make the character popular. But i think one of the big problems for character creators is that, they release a figure. But no one owns it or a able to make content for it, unless they buy it. But a vendor might not buy the figure for varies reasons. Which might not be very different from others customers, meaning I think the main reason a vendor would invest in a character is if they like it themself, and as a result of that will then make content for it. But it could also be for simply creating content for them, but if the figure is not popular enough it of course is not that attractive, so they won't buy it. So i think creating characters is a bit of a gamble, but one which can have a huge value if you can make it popular. So maybe an idea of simply offering it for free to vendors, meaning contacting varies ones and ask if they want it, might actually work.