Xavi gave him the lifeline to rejuvenate his career in Barca and he was performing well as he scored three goals and gave three assists in fourteen games. Joao's main problem is inconsistency in his performance but it all depends on Xavi and the management of Barcelona to decide if he will be signed on a permanent deal. But Atletico Madrid will not let him go for free because they are known for making money from player transfers.
the problem is only Barcelona finances. I am sure that Xavi actually really wants Felix to stay permanently at Barcelona because this coach is very confident that Falix talent and potential are very suitable to be maintained at Barcelona, while this player is really very comfortable in his career at Barcelona, as evidenced by his efforts to score every match even though some matches have decreased but for me that is very normal and all Barcelona fans and management want Felix to stay at Barcelona but are not sure whether Barcelona finances can afford to make Felix permanent.
there are several alternative possibilities if you have to keep these players Xavi will have to release several players to sell to get money to pay Felix contract.