Unclear, but maybe. I’ve done my best to include quotes from various sources below which I’ve seen so far.
From MMO-Champion:
“There will be opportunities for you to get gear to get you to where you can feel successful playing through the Zereth Mortis story content.”
“Tier sets will be available through the raids and Great Vault.”
“After Patch 9.2 releases, you’ll unlock the Forge of Creation, and earn a new currency. This currency, along with an item from PVP or dungeons, can be transformed into a tier set piece.”
From Wowhead:
“You’ll be able to find gear, treasure, and rares within Zereth Mortis, with an item level range of ~229-249. The gear will have special set bonuses like increased mobility outside of instances.”
“Cosmic Flux will also be used alongside Creation Catalyst to create tier set pieces from other activities such as Mythic+ or raid.”
“Tier bonuses will also work on all zones, there’s no Domination shard-like limitation.”
“If you don’t raid, you will still be able to interact with the system through the Cypher system on Zereth Mortis, which will eventually unlock the Forge of Creation system…This system allows you to earn a new currency, and spending it will allow you to take any item of appropriate item level and upgradable and turn it into a Tier set piece…This allows all players to engage with the Tier system…Can be obtained in the Great Vault.”
From the blue post above:
“Once players fully uncover the secrets of the First Ones, the Creation Catalyst will become available. This will serve to help anyone who’s having bad luck on a particular armor slot, or to help alts quickly catch up later in the patch. The Creation Catalyst will use Cosmic Flux in combination with an appropriate non-set armor piece to create a Progenitor armor piece in that armor slot of the same item level. The armor you transform can be obtained from PvP, Mythic+, or other new Eternity’s End content.”
[shrug]