It is not delusion it is confidence, I still believe we do have the best 11 in the world, there is no need changing things that don't need changing. Being confident in themselves will not make them weaker, they know there were bested but are smart enough to see that it won't take much to turn it around.
As for the players you mentioned, Xavi is still as good as ever though can't play as often so rotation will be important, Pique needs someone like Puyol alongside him and I think that man is Thiago Silva, a partnership of Pique and Silva would be as good as any other in the world. Pedro is still only 25 and as he is showing for Spain is still a wonderful player, with Neymar in the team it will help Pedro. Villa has been replaced by Neymar who I think will totally transform the attack for the better. Puyol will hopefully be replaced by Silva and Alves by Montoya otherwise I think the team is fine.
Valdes
Montoya Pique Silva Alba
Busquets
Xavi Iniesta
Pedro Messi Neymar
This line-up would be the best on paper in the world, and it is up to Tito to get the best from those players and I think he will. Montoya will provide balance in defence, Pique and Silva can bring out the best from each other as I feel their style would complement the others. Alba can form a great partnership with Neymar on the left, The midfield is still the best no doubt about it. The front line is exceptional, there is so much flair, skill and imagination and I can't wait to see them in full flow.
Changes need to be made and players brought in, but not many. I am very confident that the team will be back stronger than ever next season if the necessary signings are made.