Honestly, One D&D is only of interest to me -- I think to many of us -- because it led to this situation. I think the bigger concern for many, if not most, of us is what happens to other games that might or might not be based on other SRDs than SRD 5.1.So, it seems to me that (with all respect to the publishers affected). If you are not publishing and profiting from content, the only effect will be that there will be less, (maybe no) 3rd party books and suppliments available in One D&D. It doesn't mean that you won't be able to play any way and with any elements that you like. It means that no other publisher is likely to come up with something that you want if WotC doesn't. If you are publishing game content, then for better or worse, WotC will likely come after you for a (maybe large) cut. According to the OP, in many instances, they'll have a legally valid case.
Otherwise, I think for One D&D/5e in general, you're probably right.