It is still too early to pick a team for the upcoming season. All teams want to win the title every season and defend it after becoming champions. PSG is no different. PSG will definitely want to retain the title next season and see themselves as champions. But the rest of the teams will not only want to see them. Rather, they will also participate in this fight and fight for the title. The list of strong teams for the upcoming season will definitely include Barcelona and Real Madrid, along with Liverpool, Arsenal, Bayern Munich and Manchester City. Although City is not in a good position right now, they will definitely bounce back once the season starts.
Moreover, I see PSG also not really dominating throughout the competition in the Champions League. They have to work hard to get the title. All teams are improving and preparing the team for the competition. We have to see the development of some strong teams that will also compete. Their performance in the league will definitely give us an idea of how they will compete in the Champions League.
You are right, PSG has to improve more if they want to lift the champions League title again next season because other teams are really fighting hard to make sure they increase there form, next season clubs like Barcelona will be on fire because they will be very strong and inform, I'm hearing they are going for a very good player to add to there squad and that is a very good one, however PSG is very much inform and all they need to do is increase there from a little bit and they will be good to go.
For me I think real Madrid, Barcelona and PSG are the clubs that may likely lift the next seasons champions League trophy, real Madrid will grow stronger I'm sure this there New coach will make them improve but it won't be that easy for him since his just coming to the club newly but with his experience I believe he can work with them immediately, real Madrid has good players they just need to use or come up with a very good formation.