Is there a way the United Arab Republic could've lasted until our current time? If so, what would change nowadays? Would the Syrian civil war happen in the UAR? Would the coups in Egypt happen?
Best way would be that Nasser wouldn't try push too much Egyptian supremacy. Perhaps Nasser dies in 1950's and his successor is more willingful to compromise with other Arab nations.
One thing he'd have to do is get Abdul Hakim Amer off Syria, basically get him to stop alienating the Syrians by leaving them out of their own government. Good luck with that, though; Abdul Hakim was basically the head of the Army, and he still had a lot of clout. He only really lost favor/power in 1967 when his management of the Armed Forces made him a scapegoat for the 1967 fiasco.