I am going to go on a limb and say that Real Madrid will not win UCL this season as well. They are not going ot be as bad as last year, because they had many injuries last year which caused them to be worse, they will do better at group stages at least, and depending on who they face afterwards, I bet they can go even further, but they won't win.
Because every season, the best team in the world usually ends up winning, and that means, even if you are a lucky team with a good draw luck, facing easier opponents and go to finals, you will still lose at finals because the best team wins. Rare cases of smaller teams winning, but that's very rare. And at this moment Real Madrid is not the best team and PSG looks like the better team, even few others.
PSG are certainly strong contenders for the title next season, but few teams have ever won back-to-back Champions League titles. As for Real Madrid chances of winning the trophy next season, I think it's still difficult to predict, but one thing is certain, they have the complete set of attributes to achieve their ambitions. Xabi Alonso should have learned valuable lessons from his journey at the Club World Cup, Real Madrid still displayed significant weaknesses in defense.
If Xabi Alonso can address his defensive issues, I'm confident they will be strong contenders for the trophy, along with Manchester City, Bayern Munich and Liverpool. As time goes by, Real Madrid seems to will be improving, with several players who previously had long term injuries now returning to the squad, which is good news for their fans.