Please don't take this down that road again. The G sync was not a fiasco. If you bought a machine before it was available in that model then that's just the luck of the draw. ASUS has done what no other manufacturer has ever done and tried to do a retrofit, not because it was owed to anyone, just to make people happy. Well that went over like a rudder on a ducks butt and has caused them more headaches than it was worth. Should have just left it as is.
The XG2 specs thunderbolt 3 over USB C, so guess what? If you don't have USB C connector with thunderbolt 3 then its not compatible. Whats next, people with G73s going to insist an upgrade to the pascal GPUs? Maybe I should have a hissy fit becuase the pascal is coming out in the next machine and my G752VY is only 4 months old so they should upgrade mine to pascal for free? Sorry folks, technology is continuously evolving. This is not new news. The minute you commit to buy anything within a month or two something that supersedes it is announced and its obsolete in a year.
There are alternatives for thunderbolt 2, see link in the second post of this thread. The XG2 is not one of them.

“Two things are infinite: the universe and human stupidity, I'm not sure about the former” ~ Albert Einstein