Comment by foxyv
I think the technology is already there to hook into a 5g network and repeat it. However, you would need to create a network "Provider" for the mesh. Then you would need to connect all the nodes. In the end you have made one more wireless company. I think the governance model for the mesh provider would be way more important than the tech itself.
However, creating the Wikipedia/Internet Archive of wireless ISPs would be pretty awesome.
Connecting the nodes through a common backbone shouldn't be necessary in a mesh network. Nodes can provide connectivity by relaying even if they don't have access to internet directly.