I think you're overestimating by quite a bit. Unless Williams becomes the biggest star in boxing in the next year, it will never happen.
If Williams brought more to the table, this fight would be 100%. PBF would just look at that Quintana fight, and do a bigger and better job on Williams.
I say between 0-.0001%. This fight will NOT happen. I don't care if PW is the fighter of the year for the next 3 yrs, PBF will not fight him.. Hate to say it b/c I'm a PBF fan.