Israel very much depends on being the dominant power in the region. If they lose US support, things could get ugly indeed. And they are losing support rapidly now.
Because that's what the inhabitants of Mandatory Palestine did for the Israelis?
I am more sympathetic to your views regarding Syria, however. That is a less justifiable war with nebulous preventive/preemptive motivations, which is somewhat coherent on a pure self-interested security basis but is likely validly unjust under different frames of reference (morality, modern global norms and taboos, and international law).
If anything, currently it looks like Israel's relations with its nearby neighbours (excluding Palestine. Syria is bit unclear also) are improving while its relationship with the broader world is sinking like a stone.
Or more accurately, the world would let the US let it happen. And the US would probably fund it.
And the world would feel so, so sorry as they paved over the mass graves and built AI data centers and luxury hotels in what used to be Gaza.