Something that wasn't announced in the developer update was the Protoform Synthesis, a new system in Zereth Mortis that uses a mix of different reagents and items to craft new pets and mounts at the choice of the player.
This system is a new type of proffession, but wont act like a traditional profession limited by the players and will act more like the Junkyard Tinkering System in Mechagon from Battle for Azeroth.
Not much is known outside basic data mining and Blizzard has yet to talk about the system, and we will likely need to wait until PTR is live in the coming weeks to get a closer look at how it works.
According to Wowhead, it will take new currencies called Genesis Mote, Different Lattice items, and rare reagents, which are all new items which will likely drop from all activities in Zereth Mortis, however, that is not confirmed.
Eternity's End Will Have A New System Which Lets Players Craft New Pets And Mounts On Zereth Mortis
One of the major improvements so far, is that none of the reagents seem to be soulbound, so Genesis motes, and Lattice's can be sold and traded, and the rare reagents are account bound, giving reason for players to bring alts onto Zereth Mortis to obtain items faster.
We wont know how rare some items will be, or if there will be a way to obtain super rare reagents from places such as the new Sepulcher of the First Ones raid coming in Eternity's End, which could be a nice design concept, awarding players for defeating raid bosses.
The Mechagon system was a nice touch, but the Protoform Synthesis seems to be another step up in design, and hopefully Blizzard continues to develop systems that allow players to create items they want, with friendly features such as account wide progress.