hard coding of d/ dd/ id/ and idd/ Namespaces
The only "hard coding" of the d/ namespace shows such records as domains when registering with the name-tab, all others as non-standard. It's not a problem at all and would take a few lines of code to extend. Those that register via RPC calls aren't affected by this in any way. Ultimately, it's only a question of the DNS resolver which pTLD it assigns to which namespace. This is completely independent of the Core or Electrum wallets, but of course any current DNS resolver will adapt Namecoin's standard specifications.
In the beginning, there were even three independent websites representing Namecoin, while dot-bit.org was the first and for a long time the only one: