As everybody seems to be speculating here's my two pence worth...
What's probably occurred has Pep's said a good while ago he'd be leaving at the end of this season. To him it felt so far in the future that he was comfortable with that decision. Since then he seemed to have got his mojo back, things beginning to click with an almost entirely fresh squad and working with Pep2 had reinvigorated him. He knows there's potentially another chapter there in his reign at City. As the time has approached it has now fully dawned on him the magnitude of leaving. He's probably exhausted and needs a proper break, but realises in 6 months time or whatever he'd be fully recharged and would love to be able to walk back into the club.
I think he knows he's not getting it better anywhere else. The amount of control he has, the mutual love everybody has for him. Some are suggesting he might go into international football, but I personally think he'd hate that as he is so OCD. Can you imagine the amount of face scratching he'd do with players pulling out of his squads for questionable reasons? Not being able to work with players on a day to day basis etc.
I'd love him to continue, but if his decision is to leave I hope it isn't something he is going to regret in a few months time.