That isn't the correct problem. The 3rd level domain is going away, which can be reconqured via OpenNIC and mass re-adoption. There will surely be new problems, but owning will not be among those problems.

The problem is everyone else (such as email providers...) recognising your ownership.

That's why you form leverage with 22k others that are in the same boat as you. The root with the users is the root that becomes trusted, which then becomes the root that resolves. Rolling-over and allowing ICANN to quietly get away with this is exactly what they want.