The ICC directs its prosecutions against individuals rather than states. It is up to Israel's judiciary to try those individuals which is one reason Netanyahu wanted to constrain its authority. The other main reason being to allow him to get away with fraud and corruption.
The International Criminal Court is not a substitute for national courts.
It is the duty of every State to exercise its criminal jurisdiction over those responsible for international crimes.
The International Criminal Court can only intervene where a State is unable or unwilling genuinely to carry out the investigation and prosecute the perpetrators.
While it is unlikely that Israel will take any notice of any ruling on genocide it will constrain the movements of a number of Israeli politicians and members of its military if they themselves are indicted.