What might have happened differently if arabs had been able to unite as one nation after the war ?

Unity of the Arab would have shifted the world balance, and affected industries that relies on oil as these countries would likely drive the cost of petroleum very high.

The world would be clean, as alternative sources of energy such as nuclear would have been perfected by now. But luckily, there would be no terrorism, which started as a guerrilla-kind response to imperialists looking to protect important oil fields.