In as much as Manchester City is very much in form and playing good football, I doubt the possibility of them being able to win the English Premier League, the English FA Cup and the UEFA Champions League.
I think one should be able to slip from their hand. And that should be the FA Cup if Manchester United would be very much serious about this much. However, it is nothing to be hoped on because Guardiola is so crazy about these trophies.
For the moment City is fully focused to hold the Champions League trophy for the first time in their history and to achieve that I think they will have no problems to sacrifice the FA Cup final.Since this final will be played one week before the Champions League I think that City has enough time,one week to recover for the Champions League so they may well win all these three trophies during this year which would be Guardiola biggest achievement throughout his many years in charge of Manchester City.
On the other hand even Manchester United will play carefree in this game as they have got nothing to lose,so it is going to be a beautiful one to watch and also to bet on.