Arturo Vidal has already chosen his shirt number for next season. Until now, he's always worn the number 23 shirt for his club and 8 for Chile. However, according to RAC 1, Vidal has chosen the number 22 for his time at Barcelona. This number was vacated by another Vidal this summer, namely Aleix, who is now at Sevilla.
This depends on whether or not Samuel Umtiti gives up the number 23 shirt for Vidal. At the moment, he's expected to stick with 22. They also confirm that Arthur will inherit the number 8 shirt previously worn by Andres Iniesta. Although those of you with high attention to detail would have noticed that one during Vidal's presentation. Malcom will take number 7 which belonged to Arda Turan. Clement Lenglet, the other new signing this summer, will take the 15 worn by Paulinho last year.
There has been no official confirmation of shirt numbers by Barcelona as of yet but everything indicates these are the numbers the new players will be wearing this season.