Under what plausible scenario do you think WWIII happens here, of all places?
There are zero world powers that would go to war for the Palestinians over this. Russia has its hands more than full and has zero to gain in any case. China has no interest in the region except to expand its role as an international power by acting as a peace broker. The US is obviously going to take the side of Israel, as are the major European powers to a greater or lesser extent. And so on.
That leave regional powers. The only regional power that has indicated any interest whatsoever is Iran. Neither Lebanon nor Syria can be considered regional powers at this point, and Egypt and Saudis Arabia will both ultimately side with the US/Israel.
So we are left with Iran. Irans physical separation from Israel and the lack of support from the nations between them means they have two choices. They can attack by air/sea, or they can ramp up their supply and support for terrorist networks.
The former would very possibly result it the destruction of Iran. Iran has no allies that would be willing to go to war with the US in order to protect it. The Iranian navy, such that it is, would be a non-factor, and ground forces wouldn’t be able to leave Iranian territory. It would be an air war with the Iranian Air Force and air defenses up against a more advanced and better supplied Israeli and potentially US air/naval attack. The goal would be something like “degradation of armed forces and command and control” but would include attacks on infrastructure.
If Iran cranks on the terrorist network supplies and intel, it is 100% guaranteed they’re going to get an Israeli (without the US) response, which might include the destruction of Iranian military and political assets.
I don’t see any upside for Iran besides saber-rattling and maybe a perfunctory thing with Hezbollah to keep the hand in the game.