ENS has DNS import via TXT Record verification proof, so the entire DNS tree can coexist in ENS trustlessly as long as future ENS-only TLDs are chosen wisely (seems simple: just use 0x80+ Unicode.) For example, try resolving my domain, "raffy.antistupid.com" in ENS.

I believe, the ENS registry only contains "eth" as an rogue node (also "[0-9a-f]{40}.addr.reverse" is used for wallet names). Recently, ".art" started offering tokenized names, where you get both DNS and ENS.