After doing some research, as well as being corrected on my old post, I present to you my findings of how the legendary slot market might shape out in patch 9.2.
Here is the spreadsheet that contains all the data. Some takeaways from the data will follow below.
First-off, it is currently unclear whether the
Memory of Unity runecarving power creates a legendary item that has a different “Unique-Equipped” attribute than any other legendary or not. If it doesn’t, then the purchasable belt remains the only way to have double legendaries (ie having both the covenant power as well as one other power). Maybe it's a bug, maybe it isn't. My spreadsheet takes both scenarios into account.
No matter what scenario, mail will remain the armor class with the least amount of legendaries used (what else is new, right?). Plate fares better, Cloth even better and Leather remains the most popular.
As for the slots themselves, Chest, Legs, Head, Shoulders remain popular. Feet only suffers on Leather. Hands and Cape lose out almost all slots in either the Chest (true double legendary) or Belt scenario. Neck and Rings remain popular, being anywhere between 25% - 32% out of all possible slots for all recommended legendaries.
Secondly, tier sets don’t matter too much in the long run. Both the
creation catalyst, as well as the great vault, offer alternatives for obtaining the raid equipment. Also, only four out of the five slots are required to activate all effects, meaning players can go for their highest-stat slot with at least one legendary straight away and slowly get the 4 tier set items afterwards.
However, in the scenario where we can have two legendaries, then trying to get the 4-tier set bonus might become tricky for some people. Most legendary powers have an alternative slot that isn't on one of the five tier set slots (Head, Legs, Head, Shoulder, Hands), so one can craft the Unity legendary on one of those, get the tier set items on the four other slots, and craft the second legendary on any other slot.
But what if the non-covenant legendary a player wants happens to be exclusively on the tier set slots?
Right now, there are seven legendary powers that are recommended in the various guides, whose available slots are all in the five tier set slots. In those cases, if a player were to craft the Unity legendary on Chest for example, and the second legendary on Hands, then there would be only 3 slots left for tier set items, thus the 4-set cannot be activated.
In those cases, players have to choose a lower-stat gains slot for the Unity legendary instead if they wish to have it all, so there is a small market for these slots.
These conflicting legendary powers are:
Arcane Harmony (Arcane Mage if Kyrian)- Freezing Winds (Frost Mage)
- Shadowflame Prism (Shadow Priest)
- Echoes of Great Sundering (Elemental Shaman)
- Primal Tide Core (Restoration Shaman)
- Malefic Wrath (Affliction Warlock)
- Madness of the Azj'Aqir (Destruction Warlock)
If players are using these legendaries, then they might decide to craft the Unity legendary on Feet instead, or on Neck/Ring if they prefer secondary stats instead. So while not as popular as other slots, it is worth selling at least a few Cloth and Mail Feet base items.
Still, those are 7 legendary powers out of 242. Suffice to say, chest base items will remain a lucrative options.
In the end, since domination sockets are no more and tier set bonuses can be activated easier, all slots are fair game once more. However, there might be slightly-more demand for high-stat slots, Chest and Shoulders in particular since those are 1) only available starting week two of the raid and 2) are acquired from later bosses in the raid which are more difficult, and thus not as easily obtainable in pugs. Therefore, players might go for legendaries in those slots temporarily until they find reliable ways to obtain gear with tier set bonuses in those slots.