Ideally, you'd want 11 starters + 3-5 players who would be ready to start at any time in case something happens with the key players or could even become starters on their own merit. Those 5 players should include names like Turan, Nolito/RVP/Lavezzi maybe, Rafinha etc. Besides those 5 players, I'm okay with guys like Halilovic, Munir, or other youngsters being part of the squad and getting minutes in certain less-risky games.
What we should absolutely avoid is having old and well-past-their-best players stealing precious game-time from some promising youngsters.