One other thing: with Eon now doing this Rhythm Section film they will likely be tied up well into 2018. So even if there was a deal struck between MGM and whoever right this minute...BOND 25 couldn't take off any sooner than Rhythm Section is wrapped and ready to hit theatres.
This suggests Eon doesn't expect MGM to come to terms anytime soon.
Would that really prevent EON from doing a Bond film? They probably expand their team to do more than "just one Bond film every once in a while" and want to become a bigger production unity. "Rhythm Section" will definitely be a smaller-scale film that can be shot quickly and put into theatres in 2018 while pre-production and principal shooting for BOND 25 could start this year or early 2018.