If the US just quits, first of all Iraq would be divided into warring parts, the Kurds north, the Sunnis central and the Shi’as in the south. What would happen is anyone’s guess.
The Kurds are problematic, as first off the Kurds and Shi’as would want revenge on the Sunnis for they ruled Iraq under Saddam. However, this alliance wouldn’t be long lived. The Kurds also live in Iran, Turkey and Syria, none of which wants and independent Kurd states. So there would be offers and withdrawls of help to keep the Kurds busy warring in Iraq and keeping their own Kurdish populations so busy worrying about Iraq they’d have trouble fighting in their own countries.
As for Israel ceasing to exist. Nope and there are several reasons for this. Ever wonder why the Israelis were always able to beat the Arabs? Even without Nukes? Mainly 'cause Arabs are divided. Oh yes they certainly all agree Israel = Bad. Well up to a point.
Israel is a pain to them, but it does have its purposes. Let’s look at Egypt and Syria. They’re friendly even at one point they formed an actual union called the United Arab Republic, and that lasted a few years till the Syrians realized Egypt was more interested in being “Top Dog” then promoting unity and good will.
Syrians hate Israel, but they also aren’t found of Egyptians either. And Egyptians are cold to Israel but they aren’t much warmer to Syria.
But by allowing Israel to exist, Syria can be certain that Israel is so busy tied up with worrying about Egypt that it has less time to attack Syria. And it works out that having Israel occupied dealing with Syria, give Egypt a chance to deal with other things without having to worry about Israel attacking.
Even during the 1973 war, we now know Jordan warned Israel in advance, and Israel failed to take it seriously. (Kind of like Britian warning Stalin before WWII).
The big myth is all Arabs like each other and this is so far from the truth it’s laughable. The only thing Arabs have in common is dislike of Israel but once you remove that, then the next thing is to deal with the dislike of other. Israel makes the “enemy of my enemy is my friend” thing work. Look how long the Soviet, British, American alliance held up after Hitler died. Not long. Same for if Israel was to be destroyed
Israel wouldn’t even need to use Nukes against Egypt, taking out the Aswan High Dam and the Answan Dam would cause flooding and disaster in Cairo and any other big place on the Nile.
With the US withdrawl as another poster said, you’d find another regional power to step in an take its place. perhaps China would try to expand and purchase more oil to keep it’s industry running. You’d probably see a lot more internal strife among the nations of the Mideast