Oh God, i want to say something that goes against everyone. In my opinion he should bring Neymar.
One person alone doesn't make the difference, but since it's his last World Cup he would certainly work tirelessly and if he doesn't play he would try to boost the team. After all, it's his last world championship.
Only if Neymar accepts to take a proper and humble role in Brazil national team in World Cup 2026 like he promises that he won't negatively and aggressively react if Ancelotti puts him on bench and use him mostly as a substitution or send him out in middle of a match. I believe that Neymar still has many good things that can contribute for his national team, but only if he is used properly and cleverly by Carlo Ancelotti. It also requires Neymar self-aware of his fitness issues and by accept such roles, he will be able to contribute his best for the team.
Neymar deserves to be there as in World Cup, it's not strange that a player is not given any chance of playing, so even just calling Neymar like this, he should be in this World Cup. As said, Neymar is still able to contribute well for Brazil, so I see no big reasons why he misses this World Cup, that is his last one.