At what point might it be feasible for ICANN to completely open up TLD names? To allow either the "blah.com." domain or simply "blah." and have the existing ccTLDs and generic TLDs simply be "special" in that they (and anyone else who chooses to operate the appropriate servers and pay the designated fee) resell second-level domain names, perhaps with restrictions of their own choosing.

Monopoly controls might be necessary (e.g. enforced competition for sales of 2LDs as is done for the likes of ".com.", or periodic auctions for any TLD contracts which permit reselling). If you don't resell (maybe, say, ".ibm.") then different rules and pricing might apply.

That is, someone could buy or lease ".xxx." and resell subdomains; someone else could buy ".xyx." for their own site(s) and either resell or not resell. Folks globally could buy TLDs relevant to their local language rather than compromising from English.

If the ".com" servers can handle the volume of .com domains, is it that big a challenge to expand TLDs to a comparable volume with a few reserved ccTLDs and open hunting for the rest of the namespace?

I would presume this would reorganize the root server structure significantly, but is it really that important anymore if there are 100 TLDs or 1M?