The assets are “real” in the same way domain names are “real.” These are social constructs, maintained by social consensus.

It is very easy to come to a shared consensus about what address “mattdesl.eth” points to, because the history is recorded on-chain, and can be verified locally. I’m sure the exact valuation of this domain will go up and down, but as long as the the chain and network continues to exist, the asset holds value within the network, regardless of what occurs with ICANN/TLDs.