Guaridiola's contract is on a yearly basis. At the end of each season, he assesses things and goes "won the league, won the european cup, scored 1,000 goals - yup might as well stay". However this season, things haven't gone to plan. Almost certainly losing the league to Real Madrid and knocked out of the Champions League by a Chelsea team who clearly have dealings with the devil, he is pondering not signing a new deal.
A meeting took place between Barca's president and Pep, it's believed that his future was discussed at length and an official press statement is expected tomorrow. I can almost guarantee that the statement will not be that he is leaving. Although they have fuck all to play for now so it wouldn't make a difference if he said he's leaving now or a bit later. Chin up Pep, you won 14 trophies in four years and had the easiest job in the world. Now things are starting to go a bit wrong, you are leaving - I think that's a smart thing to do. What's the point in doing a job that's hard when you can quit? Leave now and save what is left of your hair.