The ICJ case filed by South Africa I feel is the only concerted campaign I am seeing that pressuring Israel against committing genocidal settler colonialism (outside of the resistance by some Arab countries).
If ICJ is not a kangaroo court they will end up ruling their actions as genocide. The evidence is plenty.
Can any good come out of it? Or is it hot air?
The point of comparison is the pressure campaign against apartheid in South Africa, which took decades to succeed.
A ruling that Israel is committing genocide could provide a lot of cover to expanding boycott/divest/sanction activities (this happened to South Africa over less, including high-profile actions like banning them from the Olympics for 30 years), and those combined with the ruling itself could solidify public consensus against Israel. Imperial governments don’t run on consensus, of course, but public discussion could go from “you must support Israel to run for even local office and you’re an antisemite if you don’t” to a contested issue, to being a liability.
This would work more quickly outside the imperial core, and as the U.S. declines that will matter more as every year passes.
EDIT: It would also have secondary impacts on all the other accusations of genocide that are tossed around more and more casually.