I think the decision what to do with Munir this season depends a lot on what club thinks about his longterm potential. If they think he can be our future "9" and Suarez's replacement in 2-3 years then he needs to play regularly at this age to develop. If they think he'll never be better than a backup we could as well keep him here with his limited minutes and then probably let him go for free in 2 years when he probably won't be good enough even for backup role anymore. I like his potential and think he can be something special and that's why I believe loan would be the best for him.
Anyway, to answer your question. I think if we bring in FC like Gameiro then we should absolutely loan Munir. If we sign Nolito then Munir could stay as he'd be the only possible replacement for Suarez without changing formation and/or playing Messi/Ney as (false) "9" when Suarez will be unavailable/rested.
MATS; SR-Pique-Masche-Alba; Raki-Busq-Ini; MSN will be our projected starting XI next season.
Then Bravo, Vidal/Jonny?, Umtiti?/Mathieu, Denis, Arda, Rafinha, Nolito?/Gameiro? on the bench. Perfect? No. But much better than our bench for most of this season with the likes of Adriano, Verm, Douglas, Sandro,...