Two serious clubs, they just need to get their transfers right, and Real Madrid has already made a move. Trent is a big signing, but I think they still need one more solid defender personally, i believe Saliba would be a great addition to the team. As for Barcelona, if they keep the same squad, like you said, they could reach the final again. If Yamal keeps performing at the same level as he has so far, that’ll be a huge success.
For now Barcelona should only sticked to the squads they have in terms of confidence because this squad is still able to bring champions League home but if they only depend on a player they have not signed yet to give them the quality they wanted they might be disarranging there initial confidence of the old squad and it might work very poorly for them, so actually even if there are some good players on there pipeline they should just have it that is an additional strength to the best squad they already have. Non of the Barcelona players has been performing badly now, so the best is depending on this season squad while even if some will later joined them.