UCL next season is still quite far away and we can't see the progress made by each team because the League has just finished. Facing the transfer season and I am sure the strength of each team will increase especially the top 5 of the standings in each League will focus on strengthening it by adding new players. What is certain is that the Champions League next season will be much more interesting than this season, Real Madrid is hunting for players, Manchester City continues to try to bring in players to win back the domestic trophy, there are so many big movements that we will still wait.
I believe all of clubs learned from the result of current result of UCL, and start to rebuild their squad again. However, i don't think we will have new candidate to compete for the UCL. I believe the clubs who will compete for the UCL next season will not much different from last season.
We will have Madrid, Barcelona, City, and PSG as the strongest candidates to win UCL next season. The candidates may increase, but i see them as the strongest teams next season.
Those teams are spending so much money to strengthen all of positions, and still ongoing now.