Sure if you ask to get rebooked to the evening flight TLL-IST you will be eligible for the free TK transfer hotel (provided that you are on the first flight to SFO the following day).

I have no idea if TK will void the voucher once it becomes clear that have rebooked and no longer are eligible for the stopover hotel. I suppose you could call the hotel a day before or on the day of arrival to confirm that there is a reservation for you?