For a deal to happen three conditions must be met:
1. City are willing to go into next season with the same number of CBs as last season (Khusa for Akanji), 2 of them being injury prone...(Reis, if he is recalled, is inexperienced at that level)
2. Akanji is ready to go to the Turkish league
3. Galatasaray are ready to pay what it takes
It is doubtful any of the conditions is going to be met. With the option we have to recall Reis, 1. is the condition most likely to be satisfied (if Pep agrees, which is not certain). Further, if Akanji is ready to leave, he might go to another English club or, say, Italy or Germany. Galatasaray seem unwilling to pay 15m for a top keeper, their willingness to pay what it takes to sign a CB in his prime from one of the best clubs in the world is highly doubtful.
I'll be surprised if this happened.