Blizzconline has come and gone, and with it we know a lot more about what is coming in 9.1. While we do not know everything yet, we can certainly begin speculating.
9.1 brings a raid, flying and a mega-dungeon
Obviously this is a proper x.1 patch with a full set of new end-game instances for players to sink their teeth into. We get access to higher ilvl gear, and harder challenges. We also get flying, which has a huge effect on players speed when it comes to gathering materials.
Materials will spike, then fall
Most likely materials used for raiding consumables will spike around the time the patch comes out, then gradually fall after that. This is the usual trend we see around this time. In Shadowlands I expect this trend will be even more pronounced as flying is coming in the same patch. I expect we’ll unlock flying a couple of weeks after the patch, and once this happens it is MUCH faster to farm materials like ores and herbs. Skinning is less affected.
New zone, new materials?
We do get a new sub zone or zone in the maw. It will be very interesting to see if there are any new materials. Either way we can expect players to change their farming routes to accommodate for flying and any new methods that are found. This will lead to changes and certain routes may end up “forgotten” which can lead to spikes in some materials. Anchor weed spiked during patch 8.2 in BfA as everyone was farming Nazjatar.
What should you do to prepare?
I would suggest stocking up on a couple of weeks worth of consumables a week or two before the patch if you plan to raid or push m+. If you want to speculate you should look carefully at material and consumable prices on your realm during BfA. Once we start getting details about material costs, new recipes and other goodies we can formulate a better approach. Assuming legendaries keep coming from crafting we will likely see a good chunk of materials spike up in price.