During the late 14th century BC Ramesses waged various campaigns in Syria against the resurgent Hittites.
What if the Hittites during the period of 1350-1100 had conquered Egypt? How long could they hold it in the late Bronze Age?
Is this even possible?
A fully-conquered Egypt is virtually impossible at this point in history, espicially at it's imperial height under the 18th and 19th dynasties.
Nonetheless, there is an intriguing episode in the closing days of the 18th dynasty, where the Queen of Egypt (Ankhesenamun) requested to marry a Hittite prince (Zannanza) because the Pharaoh (Tutankhamun) had died with no living heir. However, the King of Hatti (Suppiluliuma I) waited too long to respond, and by the time the prince arrived, a new Pharaoh (Ay) had been crowned and the prince was killed.
With this given, it is possible that Egypt can be ruled by a Hittite king, but not directly conquered by them.
The New Kingdom Egyptians would have probably fought tooth and nail against the Hittites, I doubt they could effectively extend their power past the Delta, much like the Hyksos. Perhaps the Hittite emperors Egyptianized themselves thoroughly, but that would likely alienate them anyways with the rest of their empire, and given the sort of nativism ingrained in imperial Egyptian society that probably wouldn't have been enough anyways.
I should say, with the Zannanza scenario the fact that the Queen made that arrangement, not the acting Pharaoh doesn't speak well for how long-lived it might have been, had Suppiluliuma responded more promptly. Especially since having a foreign prince marry a Egyptian princess is directly the reverse of the standard Egyptian diplomatic protocol of that period.
Now, a more Hittite near east in the scenario they survived the Bronze Age collapse beyond just a few rump states in syria, that would be interesting. How would they have fared against the Assyrians, for example?