Blizzard clarified the new PTR locations and what is and will be running on each instance in the future.

PTR (Source)

Greetings!

You might have noticed that we’ve done some shuffling lately on the Battle.Net App for PTR to support concurrent test environments. Starting with today’s PTR build, here’s a quick look at all of WoW PTR to make things more clear:

Public Test Realm (DF 10.1.5)
Current Status: Running 10.1.5
Realms: Iridikron with connected realm Fyrakk, Vyranoth with connected realm Raszageth

Public Test Realm (DF 10.1.0)
Current Status: Offline. We’ll use this for the next PTR cycle after 10.1.5 (and will be renamed in the BNet App)
Realms: Nobundo, Lycanthoth with connected realm Broxigar, Bendictus with connected realm Anasterian

Classic Season of Mastery PTR
Current Status: Offline. This will be go back to being used as a test environment if/when Classic WoW needs it (and renamed appropriately)
Realms: TBD

Public Test Realm (Wrath Classic)
Current Status: Running 3.4.2, Call of the Crusade
Realms: Classic PTR Realm 1, Classic PTR Realm 2