I can point to a dozen games that involve rolling three or four d6 for abilities, or a point buy based around a medium attribute of 10. Given that GURPS, which was published in 1986 and which offered both methods, has not been sued out of existence, I think Paizo is safe. Runequest has "basically identical" character creation, as does Dragon Warriors, Call of Cthulhu, Villains and Vigilantes, Dragon Age, Hero System, Palladium Fantasy, etc. Runequest was in fact published in a form under the OGL, as was BESM d20, SAS d20, Adventure! d20, Mutants and Masterminds... Unless WotC is ready to pump, probably, tens of thousands of dollars, if not millions, into remedying the situation, the time has long past where challenging that is practical.
Further, since Green Ronin stated early on, explicitly, that they wanted to include character creation, are licensees under the OGL, and WotC was doubtlessly aware of their intentions, WotC would be a bad actor to implicitly countenance that use of the license, only to turn around later and cherrypick lawsuits. Not that they couldn't, just that they would have be both unethical and acting contrary to their own financial interests at the same time, which makes the possibility unlikely.