My preference would be to maintain the OGL as is but have them issue v1.0b with the language that it cannot be revoked or deauthorized or remove any of the rights or reserve any new rights that 1.0a didn't reserve.
If they want to have a OneD&D compatibility license where they can insert whatever reservations of rights and terminations clauses and royalty fees in that, then that's the appropriate place to do so. This can also allow them to restrict video games, novels, etc., which is appropriate in a compatibility license. This is also the place they can control their brand by preventing things they view as bigoted or otherwise unacceptable. I don't think those restrictions belong in the OGL that is licensing just the base rules mechanics and there's no real IP to protect in the SRD the OGL applies to that would dictate keeping it out of any medium. In regard to bigotry and everything that is in that vein I don't think it belongs in the basic OGL mostly because who is going to make that determination? If someone produces something the community sees a bigoted then the community will make that product fail. WOTC certainly shouldn't have any control over that in the OGL, they have shown they cannot be trusted as a steward.
For me Umbran's number 4 has me conflicted. I think caps might be a better solution, I can't make myself take the turn necessary to have the licensor take a piece of profits since those are easily written away as expenses, Hollywood has shown us how to do this for decades. The accounting is cleaner and better reportable as gross revenue. A smaller percentage and/or capped amounts that are predictable. but again, I think that should be in a compatibility license not the basic OGL license.
Since we are in a very different marketplace that we when the OGL launched or even when 4e came about I think WOTC could build an attractive walled garden to incentivize creators to enter into a compatibility license and get much of what they were trying to force down our throats but without the damage to an entire subindustry that helped make D&D the market beast it is today not to mention those creators that built upon the blocks to innovate into other directions than supporting D&D.
Gil