"...but right now, just a rush implementation to satisfy Genesis compatibility would be a waste of resources."

This is true, assuming that Genesis will have no effect on Poser sales. Right now, (especially if you go by comments here) that is the case. Whether Poser sales will remain unaffected by not fully supporting DAZ content in the future remains to be seen. It depends on how most new/upgrading users would prioritize DAZ content support vs. other possible features, e.g. better lighting, faster rendering, soft body dynamics etc.

When talking about how many people will 'use', weight mapping, or any feature, you have to distinguish between the feature and its output. By definition, everyone using a weight mapped figure will be 'using' weight mapping. That is entirely different from using it, or again any feature, to actually create/alter content. Unless you believe that a substantial majority of users fall into the latter category, then a better question might be how many content creators will use a given feature in the content that they distribute? Beyond that, you also have to consider how many people would buy an item because it incorporates a feature vs. a similar one that does not. Feature X also needs to provide discernable improvements in the useage scenario that is typical for the given user, in proportion to any increased cost in terms of price, render time, ease of use etc. Taking that into account, I wonder how many people would upgrade to 9/2012 or DS4 just to use weight mapped content?

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken