Awesome news, really glad that the legend stays with us. Having one more veteran leader in the dressing room is very important and guys like Rafinha and Rakitic to an extent can learn so much from him. He'll be the captain, the proxy between Lucho and the team, essentially act as a player-coach, and be an example for the youngsters. He may accept a smaller role and play less this season, but he still has a bigger responsibility now that he's a leader for everyone else and has to exercise self-restraint to let the new generation shine.
Having him around helps to keep the feeling that not all of the club's old 'heritage' was lost in this complete renovation. The new guys are going to be valued members of the Barcelona family along with the ones who've remained.