Arthur's arrival at Barcelona could force the club to loan out Yerry Mina to ensure they don't go above their limit of three players from outside the European Union.
The three slots are currently filled by Mina and Brazilian duo Paulinho and Philippe Coutinho.
As Grup 14's Rafael Hernandez noted, the club are hoping to get Coutinho a European passport to circumvent the limit:
According to Sport's Lluis Miguelsanz, Barcelona have requested Coutinho be allowed a Portuguese passport to grant him dual nationality, as his wife is from Portugal.
However, Miguelsanz reported Arthur is due to arrive in the summer, while sources close to Coutinho indicate he won't receive his passport until after January 2019.
With Coutinho and Paulinho cemented in the squad, Barca may therefore have to vacate Mina's position for Arthur and look to send the Colombia international out on loan.
The 23-year-old arrived from Palmeiras in January but has only made two appearances for the La Liga leaders.
Football writer Rik Sharma noted the centre-back's impressive goal record over the course of his career:
He netted nine times in just 49 appearances for Palmeiras, having earlier scored 12 in 124 outings for Santa Fe.
He dispatched a penalty as Barcelona beat Espanyol in a shootout in the Supercopa de Catalunya earlier in March:
The defender is the most expendable of the three non-EU players in the squad, though, so he looks likely to move on until Coutinho's passport situation can be rectified.
While it's not ideal, he may end up playing more first-team football than he would have by remaining at Barcelona next season, so it could help him develop further before returning to the Camp Nou better able to contribute.