Morgan Day did a really meaty systems interview. wowhead has a summary here:
https://www.wowhead.com/news/the-starting-zone-patch-9-2-interview-with-morgan-day-anduin-encounter-sepulcher-325004For world-first raiders, a big question is how much variance there is in a character's power on mythic week and what the guild can do to minimize that variance. Shards of Domination were terrible from that point of view because (1) there was a very large power variance depending on whether you got a shard set in the first two lockouts, (2) the only way to minimize variance was to run multiple alts of the same class, and (3) the system went in too late to prepare those alts. So Limit and Echo did a lot of benching based purely on who was lucky enough to have the unholy bonus during mythic week. In 9.2, set pieces will drop directly through personal loot (no tokens); minimizing variance will probably require heroic split raids with as few classes as possible (e.g. ten demon hunters, ten priests, ten mages, where only 1-2 of each class is a mythic main). But at least that is known long enough in advance to prepare for it.
For progression but not top-tier players (whether in M+, raiding, PvP), a big question is how many weekly chores are needed to obtain the maximum player power, even if the power delta is small and only available after 1-2 months (like adding sockets to gear and upgrading conduits in 9.0 and 9.1). From the interview, it sounds like 9.2 could be lighter in the chores department. The Cipher of the First Ones system supposedly won't have power progression tied to it (except in Zereth Mortis itself); power such as legendary upgrades will instead come from a currency called Cosmic Flux which can be obtained in many ways, similar to Echoes of Ny'aloha at the end of BFA. A risk is that the calendar-fastest way to maximize power will be to do some amount of
everything during the week to maximize flux income, but we don't know yet if that will be the case.
For curve raiders, chores matter somewhat but it's less important if the power deltas are small, and typically it's possible for a significant fraction of the raid to ignore other content. Morgan made it sound like there won't be extremely long fights like Sylvanas in this last raid, since the story doesn't require it. We'll see.
I had one point of clear disagreement: Morgan mentioned that they liked introducing new dungeons as a mega-dungeon first so that players are more familiar with the dungeons by the time they are available in M+. But this time around, there wasn't a reason to re-run Tazavesh after finishing it on hard mode, so there won't be a lot of familiarity. I recall there being more reasons to re-run Operation Mechagon. I'm not necessarily asking for that (it's hard enough for my dungeon group to find time for the M+ runs we want to do), but I don't think they are getting much mileage from the mega-dungeon period relative to what they are losing from the long delay before adding it to the M+ set.
