Your analysis is right, both teams are very making good preparation for the next season business, it is very obvious that Realmdrid will give a good fight time although time will tell, we have seen seen xabi playing three man defense in the ongoing club world cup but let see if this pattern of xabi can be sustained and keep yielding good friut for the club, personally I will want to experience a tough battle for the league next, not only from both teams but other clubs that will be contending for the league title next season, although we know that Barcelona and Realmdrid are the teams to look up to in that league, Athletico Madrid would've been one of them but they behave like arsenal of England sometimes.
In La Liga there is no competing team that is able to break the dominance of Barcelona or Real Madrid in terms of competing for the championship title so in this League it is only about the two teams every season. This is why if you look at the quality of the teams that will be the title contenders it will be a little easier because Real Madrid and Barcelona themselves have the most chances. The three defender strategy installed by Xabi Alonso is not yet perfect because there are still weaknesses as happened in several matches in the Club World Cup. Atletico Madrid played inconsistently and they always lost the momentum to maintain consistency and you are right it is almost the same as Arsenal in the Premier League.
You are right. There is a lack of teams to compete with Real Madrid and Barcelona, and Atletico Madrid's potential has already been exhausted. However, I think Diego Simeone can still bring something good and great to the team and he has enough confidence to inspire the team. His contract with Atletico is currently until 2027 and in the meantime, the club top management may still be positive about keeping him as the team coach. However, there has been a lot of criticism about him and many are criticizing his continued role as coach of the team. Some critics have advocated his dismissal. In the 24/25 season in La Liga, Atletico Madrid was at the top several times with impressive performances but they fell behind due to poor performances. I think Atletico Madrid potential is not very low compared to Barca and Real Madrid they still have the better players to reach the top position.