It looks like this is the plan for 2011-2012:
Goal: Valdes, Pinto in Copa del Rey
Fullback: Alves and Abidal, Adriano subbing a lot for Abidal and almost never for iron man Alves
CB: Pique and Puyol, Adibal and Masch the alternates
DM: Busquets, Masch starts 1/3 of the games
OM: Xavi and Iniesta, Cesc playing a lot, Thiago and Keita some.
Right and left forwards: Villa and Pedro, Sanchez playing a lot, Afellay some
Center forward: Messi, Villa when Messi rests
That's 19 who will play, with 16 playing quite a bit. This will be a much better rotation than last year at both forward and midfield. Only five for four back line positions until Puyol returns, which seems crazy thin except Pep won Liga and CL last year using only that many. Maxwell was the alt fullback until Adriano took his place, Busquets and later Masch were the alt CBs when Puyol and Abidal went out.
These 17 non-goalies will do some position changes, like how Masch became a CB and Afellay became a forward last year.
If any of Bojan, Jeffren, Maxwell or Milito return, it will be a very sad year for them remaining on the bench all year.
It won't matter who else might be on the bench. Fontas, a new or promoted player or two, they will almost never play. Pep only uses a limited number of flexible subs.