However, the solution should not and cannot be a global routing table. Aside from privacy issues, routing tables are very expensive. It needs to be decentralized, done on or at least near the endpoints, similar to programs like mosh, wireguard etc. Though there are certain security and privacy trade-offs in mentioned protocols that may not be appropriate.

The "flat address space" idea however is completely ridiculous. That would mean every node on the internet keeping track of the path to every singe other node. This is what ethernet does and it barely scales to ten or so thousand nodes. Routers are already struggling hard with the 700k table entries we have for the IPv4 internet. To the point where providers actually wrap IP packets inside of simpler protocols once they enter the network.

We need some kind of hierarchical addressing that expresses the location of a node in the network. We know this works. We just need the layers above not to rely on those addresses staying constant.

If anything, we need a more hierarchical structure, with stricter separations by, e.g. Continent/Country/Province and possibly down to street or even house level, so routers can more easily just throw the data in the right general direction. Note the obvious privacy problem there.