4 important aspects for Pep leaving Barca and Bayern.
1) Annoying press was a huge reason why he left Barcelona. England are not even half as annoying, and he seems pretty comfortable.
2) Players effort and humility. Last year at Barca some fractures with Pique and even Messi happened. Pep wants their players with hunger, and the reaction we had after Tottenham is indicative of how much more hunger our players still have.
3) Having a challenge. Pep loves managing week in and week out (basically leagues), and right now PL is by far the biggest challenge. 7 teams that have similar budgets, and the remaining 13 are still very competitive and can sign 40-50 m players. This is why he left Bayern (and the management on Bayern being annoying to work with). Also, we are gonna sign new 4-5 new players (most likely) and Pep loves working and molding new players.
4) Good organization and environment. Txiki, Ferran and Kaldoon. Enough said about this.
I would be shocked if he leaves after winning the treble. And if he does, it's because he wants a break. From the press conference, it doesn't seem like he wants a break at all. He constantly talks about how energized he feels because we are still fighting for everything