It´s apparent that EON, MGM and the next distributor will have had conversations about the future of the Bond franchise, and EON will not have attended those without a concrete idea about plot and casting. They are professionals, and nobody goes into a meeting saying: well, I don´t know... They go in and say: this is what we want to do, and this is what we have to deal with.
Even if the smokescreen for the media (including Baz) has been "nothing´s certain, we don´t know yet", there will be many plans in place. Hiring P&W now definitely means: we want a shootable script in the near future, boys. And this being a Bond film, it means: these are the action sequences and locations we have mapped out - so incorporate them.
I also believe that EON will have been in contact with P&W constantly since they are their go-to-guys (their last interview again must have been another smokescreen, designed to keep the media off the scent), and either EON had started out with other writers which did not deliver or deliver enough so P&W have to shape that work into something workable - or EON has decided to employ only P&W because they know P&W can deliver on time for a projected shooting date at the end of the year.