After many years of asking for it, apparently players will now be able to access Ordos in Timeless Isle without having the original cloak. To quote a blue reponse on the Community forum:
“The original legendary cloak questline will not be available. You’ll want to reach level 70 on a Timerunner and receive the legendary cloak appearances on your Cloak of Infinite Potential to enable access to Ordos for this event as well as the rest of your WoW account.”