This I agree with!
We also have to consider if Masch is up for being backup DM in the summer, if not than we need to replace him to. Xavi is not getting younger so we need to think about maybe buying a CM/DM.
Another thing we have to consider is our forwards. Atm we have Messi, Pedro, Neymar and Alexis who should all stay - so we only have 4 players for 3 positions (if Tata finally grasps that Cesc is a midfielder and not a striker). Not sure of Delou is up for it yet, and Cuenca is to injury prone + not sure if good enough. Getting a Larsson type of 9 would be my choice.
I think goalie and CB are much more important atm. Xavi stil will be there next year and you just need him in the important games. Sergi is good allthough you might consider somebody like gundogan
the attack is fine for the next years. messi will come back, Delofeu and Dongou should get their chance next year.
if you want a larssontype of player maybe try Klose.
experienced, cheap, won't complain on the bench, a real pro, knows where the goal is and the kids could learn a lot from him.