I can think of no good solution. Here's a mediocre solution, laden with violations of human rights and prone to failure and going back to square one:
1. Israel retakes Gaza, eliminates Hamas and installs a puppet regime of Israeli Arabs. With cues from China, Orwell and post-WW2 Germany, Gaza is made into a complete panopticon - cameras, internet monitoring, a network of spies, you name it. This is very problematic, but it's preferable to collective punishment. This is meant to be temporary.
2. Using American and European money, The homes, schools, hospitals and stores are rebuilt. Massive famine relief is performed. A UBI plan is initiated to allow the Gazan economy to get back on its feet. It is important that Gazans will feel that the post-defeat period has been a big step upwards in terms of life quality.
3. Using Saudi/Emirati money, the mosques are rebuilt. They are made to be the fanciest, most beautiful mosques in the region. Streets and institutions are named after Palestinian poets and artists (not terrorists). It is important that Gazans won't feel like their culture is being erased.
3. A new education curriculum is developed which fuses western education, progressive values and Muslim tradition while discouraging political violence. There are lots of art, music and sports scholarships.
4. Safe spaces for LGBTQ people are established. These will cultivate a local progressive movement that will be in touch with Israeli leftist organizations, and will serve as an additional front against Islamic fundamentalist violence.
5. Using Saudi/Emirati investments, an artificial island is built in front of Gaza, and on it - hotels and gaudy tourist attractions. This is for developing the economy.
6. Gaza's tax system is made to attract international companies and billionaires. They will have an interest in a peaceful Gaza and will pull the strings to keep it so.
7. As Gazans become deradicalized, they get more and more permits to enter Israel and visit the West Bank. This improves their economic prospects.
8. Once Gaza is no longer a threat to Israel, pressure is enacted on Israel to give Gaza independence.
Roger Williams, is that you?
Yes, it is paternalistic. Part of my point was that the situation in Gaza is so dire in terms of life quality and radicalization that a dystopian colonial social engineering project would be almost humane in comparison. This is where the great challenge lies - how to ascertain that after Hamas is eliminated (and it must be; after October 7th Israel will not rest until it's gone), Gazans won't promptly create its sequel.
But yeah, everything past the deradicalization stage is just a suggestion, and if it's successful, Gazans get to choose the direction of their economy.