Originally Posted by ISTFlyer

1- I don't think the seats are pre-assigned unless someone paid for them previously. I have flown on a SU A350-900 on a domestic hop to Ankara and the seats were available for purchase until the time of departure including online check-in.

2- No, TK would still sell the seats for the same price as they don't have any dynamic pricing for seat selection.

3- At the airport, agents could override any seating charge and assign you those PE seats as well as any emergency exit row ( even for non-status passengers ) for free. However, at online check-in, a Star Silver ( including Miles&Smiles Classic Plus ) would have no additional seating benefit.