Turkey may very well be cognisant of the increasing sentiment that the F-35 sale to Turkey is not a good idea for a number of reasons. If this were to be the case an indigenous product would be a useful fall back.
Turkeys recent purchase of the Russian missile system did not go down well either with NATO or the US. The blocking of F-35’s to Turkey would certainly create a big problem problem, but it has already been notable by the lack of information for a while now, however one that may well have been in part anticipated. No crystal ball was needed to see, it is one that has been growing quietly for a while now.
There have been cancellations before of major military contracts, and country to country collaborations, US F16’s to Pakistan, India and the PAK FA T-50, Russia’s French Mistral ships, and while they undoubtedly can create major problems they do happen.
LM had indicated some time earlier that Turkey was not indispensable to the program, and no doubt has already been studying alternatives. The US military and State Department will also have have been examining the whole situation carefully. Erdogan has been quite strident over the last couple of years and Turkey’s commitment to NATO questioned.
While it is indisputable that Turkey is geopolitically important it is also idisputable that there has been a drift in the direction of both Russia and China, and it’s nomination as the leader of the Islamic Military Alliance.
Even recently there has been friction.
The U.S. alliance in Syria is falling apart as Turkey wages its own war on “terror”
Turkey’s choice of the Russian Missile system is another irritant and potential sticking point.
Turkey Dismisses U.S. Warning Against Buying Russian Missile System
If Turkey buys the Russian S-400 missile system, it can't be allowed to buy the F-35 fighter jet
The sale of F-14’s to Iran, and the Shah’s quickly following ejection remains as a historical reminder that things can go very sour very fast.