The territories gained after the 1948 War are necessary for Israel’s existence as the previous borders were simply indefensible. Israel will never go back to pre-1948 borders no matter what and I don’t think the international arena should even waste time trying to implement this idea.
Also, about the ICC. By going to the ICC, Palestine would be violating the Oslo Accords which explicitly mentions that both parties ought not the take unilateral steps because it’s impossible to solve a conflict no matter how lawfully or forcefully you engage in it unless the other side isn’t compromising (and in this case we are talking about a strong state, not just a kid who can be punished by his/her teacher). Also, since Fatah is now in a unity government with Hamas (yet has requested the Arab leaders to rid Gaza of Hamas) and Hamas has repedeadeltly broken rules of war by summary executions of alleged Israel collaborators, indiscriminate firing of rockets, targeting civilian areas with rockets, not wearing uniforms which causes civilian casualties in urban warfare and probably much more. So, Hamas leaders are most certainly guilty of their crimes and Abbas is now cooperating with them as they are in a unity government but I don’t thin the law applies to Abbas too since it shouldn’t be retroactive and unless Hamas starts raining rockets again, Abbas should be safe.