It's possible and a threat that they're positing. Technically, VTTs who don't sign 1.1 can't host rules sets, modules, etc., for any OGL content. That means if you're playing any edition of D&D, Pathfinder, etc., the VTT would be in violation and would be sent a C&D or sued. VTTs will have to pull that content - which is the lion's share of players (from what we've seen posted on Fantasy Grounds' and Roll20's reports. So losing something like 75% of their players (and paid customers) isn't going to bode well for these companies, right?
So, yes, they are planning on indirectly shutting down VTTs. Everything is going to the OneD&D VTT. And do you think they will allow other games to be played on that platform?
They are trying to monopolize and crush the entirety of the industry.