Adding TLDs doesn't open up the domain space; it closes it. The domain name system was designed to expand downwards, by adding more hierarchies. Downwards is where the space is. Expanding upwards is limited.
The racket ran out of space selling keywords inside .com, where this was originally meant to be confined. Once they finish selling keywords at the root, that'll be it.
I don't know. I don't think nested hierarchies is a thing. I mean, I guess you have the "Go Network" go.com example (disney.go.com). But I think the ship has sailed for deeper hierarchies. I really don't want an email address that is: taftster@foo.bar.baz.example.com
I didn't make any judgement on whether it is a good or bad thing. The fact remains: don't delude yourself into thinking that adding a TLD free-for-all opens up the space. It doesn't. It closes it.
The current "problem" stems from the fact that .coms are full. Once the TLD space is full, the same problem will remain. Everyone who wants one cannot have a memorable name in a flat namespace. There are too many people and there is too little room.
When that happens, I fully expect that as the value of available domain names go up, people will invest in expensive domains (blah.com) in order to treat them as "2LD"s and sell its 3LDs (xyz.blah.com). But it won't happen while there are 2LDs available for the exact reasons stated above (nobody wants a subdomain when they can have an actual domain).
Adding TLDs doesn't open up the domain space; it closes it. The domain name system was designed to expand downwards, by adding more hierarchies. Downwards is where the space is. Expanding upwards is limited.
The racket ran out of space selling keywords inside .com, where this was originally meant to be confined. Once they finish selling keywords at the root, that'll be it.