If Israel genocided Gaza, they would face severe retaliation at home and around the world. There would still be no peace for them. When Israel gets rid of Hamas, they plan to control Gaza for an indefinite period.
"Netanyahu told ABC News that Gaza, which Israel captured along with the West Bank and east Jerusalem in the 1967 Mideast war, should be governed by "those who don’t want to continue the way of Hamas."
They really have no choice but to control Gaza.