Unpopular opinion: we should sell Busquets
Before you all attack me, Busi is the best DM in the world, he can't be replaced, I would never sell him in normal circumstances. Here is the reason why I would sell him now, Barca is not using his full potential, they are maybe using 50% of his ability. He is not the same player in a double pivot like he is as a lone pivot, and that is a big problem. Busi is still great for Spain, there is no denying that, but for Barca last season he was a defensive liability in some matches, he was making mistakes I have not seen him make since his first season at the club. The main problem is, the club will keep playing a 4-4-2/4-2-3-1 formation as long as Messi is here. While Busi thrives in a 4-3-3, Messi can't play in that formation anymore. He can't play as a lone striker or a RW. If we want to get the best out of Messi we need to keep playing 4-4-2/4-2-3-1, but with that formation Busi becomes a liability. We can either get the best out of Messi or Busi, but not both at the same time. While both are important for Barca, there is no arguing that Messi is much more important.
Busi will be 30 in a couple of days, he is slow, and he is already declining, he doesn't strike me as a player that will have a long career at a high level, 2, maybe 3 more seasons at max. Combine that with Barca not using him properly and you get the picture why I would sell him now, while he still has a big enough price. Personally I would sell him to City for around 100-120 mil, Pep would gladly give that money, and get Kante for around 80. Kante would be the perfect player to play alongside Raki in a double pivot. Our midfield would get much faster, and more aggressive.
We need to start rejuvenating our first eleven, Pique, Alba, Busi, Raki, Messi, Suarez all are around the same age (30-31). All of them will need to get replaced in the next 3-4 years, that is 6 first-teamers that will need replacing at the same time if we don't do it gradually, starting this summer. All of the above mentioned players are much more comfortable in the 4-4-2/4-2-3-1 formation except Busi, that is why he is the first that should be replaced.