If Egypt somehow magically changes their mind about accepting refugees then presumably large numbers of Gazans would want to go there, but that's not an action taken by Israel. Not sure this question makes sense.

Does having your apartment block destroyed resulting in you leaving gaza count as "ethnic cleansing"?

https://www.axios.com/2023/10/13/israel-gaza-hamas-evacuate-un-ground-operation

Better market here:

https://manifold.markets/MilfordHammerschmidt/will-the-palestinian-population-of

Will the Palestinian population of the Gaza Stripe drop below 2,000,000 before 2025?

50% chance. Currently at 2.3 million, according to Wikipedia.