Lebanon main govt will recognize the game and let it be. Hezbollah will be upset and launch the same rockets they were going to launch anyway.
This is the optimistic output, and I hope that's what happens. But this is a major escalation from Israel, aiming to provoke hezbollah. It would not be any surprising if Hezbollah escalates back accordingly.
Israel does not gain from this assassination in the way you think. Hamas' effectiveness is not reduced one bit and Israel knows it. Their only goal is to escalate with Hezbollah, and justify expanding their attacks into Lebanon.
I just hope that Hezbollah makes a calculated response that does not give Israel the pretext they're looking for. So far, hezbollah has only attacked Israel in Lebanese territory, not Palestinian. Attacking Israel in Palestine would be a significant escalation but also an appropriate response.
I think Israel lives on its people considering Arabs their enemy. It makes them tolerate a lot more from their government that they otherwise wouldn't.
I think they rather suffocate Palestinians slowly rather than end them all at once.