Stone Age settlement found under the sea in Denmark

> As today’s world faces rising sea levels driven by climate change, the researchers hope to shed light on how Stone Age societies adapted to shifting coastlines more than eight millennia ago.

Unfortunately I don't expect there is any particularly reusable solution to be uncovered. Ancient peoples facing rising tides almost certainly just walked a bit inland and built new huts there. They probably thought nothing of it. They were a far more physically mobile culture, without great dependence on immense, immovable infrastructure - nor on rigid land ownership rules.

Our culture's migration will be entirely different.

>nor on rigid land ownership rules.

Land ownership was formalized about as soon as there was a reason for anyone to own land - i.e., as soon as any given people started doing pastoralism and agriculture.