Turan is my favourite non barca player in the league, and I would love to have him here.
However,, if we are getting Pogba (which seems fairly likely), I doubt we'd need him - I mean it would obviously be better having him than not having him - but since we can't look at absolutes,considering the money, playing time, etc. it probably would be a bit unnecessary - seeing Iniesta Raki Biscuits Pogba and Rafinha should be the ideal number of players to rotate those 3 midfield positions.
However, that's assuming the Don's level doesn't suddenly deteriorate further - in which case I think we'd have to spend on a marquee signing in 2017 anyway (unless Rafinha becomes the shiznitz)