If Barça do bring the Brazilian star back they'd need to get rid of another non-community player, either Vidal, Arthur or Malcom.
Barcelona seem to be getting closer and closer to bringing Neymar back to the club, with PSG having lowered their demands for the Brazilian to around €130 million plus two players. The player himself has made it clear he wants to go back to Barça and at the club itself the momentum seems to be swinging in favour of re-signing him despite the pain the player caused when he left for PSG and doubts over his lifestyle.
Barcelona already have three non-EU players
If Barcelona do bring Neymar back the transfer would have a direct impact on one of Vidal, Arthur or Malcom, who are the three non-EU players currently at the club. Under LaLiga rules each club can only have three non-EU players in their first team squad.
At least one of the three would need to leave to make way for Neymar, who has a Brazilian passport. The most likely would be Malcom, who signed for 41 million euros in 2018 but has failed to convince Valverde and has failed to perform to the level expected of him at the Camp Nou. Borussia Dortmund are said to be keen on Malcom, although Barcelona would prefer to sell him to a Premier League club.
Vidal would be an easy option for Barcelona to sell, with Inter Milan keen and a major offer having come in from China for the Chilean, but the club don't want to get rid of the player yet and expect to hold onto him for one more year.
Arthur, who is a good friend of Neymar, started well last season, and although his performances tailed off he's expected to be given the chance to show what he can do in 2019-2020.