I don't think so. he loses more chance to win UCL next season. I think that barcelona will not able to perform the same like manchester city did next season. Barcelona is bad club when it came to the european competition.
Do you remember when barcelona was losing in UCL last season and it's also losing in UEL too? That proves that if barcelona is not a good team for european competition.
gundogan was making bad mistake. Silva shall not follow him.
Obviously if we talk about the quality between Manchester City and Barcelona, Manchester City is far ahead from Barcelona. Barcelona isn't have a lot money too, so in terms of quality they're lose, in terms of quality, they're lose too. But Gundongan still want to join Barcelona, obviously there's a strong reason involved, what I think he's want to take a challenge and improve his quality.
Ikay Gundogan might not be looking to win another champions league next season buy he has his reasons of going to Barcelona. Some players when they have won many titles as they like, they no longer chase trophies. They will begin to consider place of settlement after retirement just like Messi did.
It is players like Harry Kane that should be disturbing himself about title wins and not Gundogan.
Man City are probably the best club in Europe right now, but don't forget how they only managed to push Arsenal out of first place at the end of last season... So there are strong clubs in the EPL now too... I think that next season Man City will not be as easy as last season and I don't rule out the possibility that they won't be able to win again...
Many clubs will obviously contest in this coming season but it seems that Manchester City will remain the favorites for both EPL and CL. They can still win both but they will not win treble again.