I think it will be decided after pre-season. Right now he is still B team player, because Lucho confirmed only the promotion of Munir and Sandro but I want Alen to be promoted too if we can't get Denis back from Sevilla.
We still have Rakitic, Iniesta, Rafinha and Roberto till January.
I know, Roberto is lately a defensive midfielder but he is still better Cm than Halilovic currently, and he has played a lot of 1st team matches either as a Cm or Dcm.
From January we will have Arda and maybe Denis Suarez, so Halilovic would get zero minutes in the 2nd part of the Season, unless if we play a 2nd div team in a cup.
So, he wouldn't play too much till January, and after January he wouldn't play at all.
That is not the best solution for a player who needs playing and developing now in crucial parts of his development.