He's keeping his options open - he knows he is, unfortunately, declining in the sense of being able to do it at the top level consistently. His legs are slowing down while his head is still working as it always has been. Must be so frustrating for him really.
Unless he adapts and changes his game, or Pep changes how he's used, then he's probably thinking he can earn a fortune playing within himself elsewhere rather than being a deputy in this squad.
It's like the final, we'd have been better off having him come on after an hour rather than going off with a whimper 55 minutes in having had a mare.
Seeing Foden step up centrally will have no doubt changed both his and the club's perception of things as always.
Personally hope he stays, though, but we can't be relying on him week in week out anymore IMO.