I just went onto the PTR to see how honor gear will work in 9.2. I made the following table showing the ilvl at every rank as well as the honor required to upgrade the gear to rank 7.
The good news is that I was able to upgrade the gear to rank 7 without having to complete any of the new quest for 9.2, i just walked up to the vendor and was able to upgrade. So assuming nothing changes we should be able to get to a level playing field (minus stat weights of conquest vs honor gear) on the first week(s) of the patch before the new season starts.
The bad news is that we will be losing the 40% extra honor buff from spoils of war in 9.2, meaning the 66k honor you need to obtain will take a lot of grinding. Ideally upgrade prices for honor gear should be halved. Honor gear is not an end goal, it is meant to be replaced throughout the season with conquest gear. So having a massive honor grind attached to it does not make sense.