Turkish President Recep Tayyip Erdogan, in a speech to fellow party members in Sakarya, promised to “revise the outcome of World War I and annex Syrian territories (formerly Ottoman provinces) into Turkey,” Telegram channel “Turkey’s Top News” reported.
I presume that the other NATO countries will refuse to recognize annexed areas as part of the territory of Turkey and so they will not be protected by the treaty. Note how the treaty already does not protect even internationally recognized parts of certain member countries (for example Hawaii).
What if the Syrians carry out retaliatory strikes in Turkey?
From when Turkey first invaded Syria:
Source.
Syria no longer has the military power to pose a real threat to Turkey, so they likely wouldn’t invoke article five anyway. Plus, if they invoke article five, they would then have all of NATO camped in their backyard. That would put a serious damper on any of the more egregious things Erdogan wants to get away with.