I have no idea what it has to do with SL having 3 or 2 major patches. Revealing 9.2 now would be stupid cause it takes whole attention from 9.1 which isn't even on PTR.
I have feeling 10.0 may be massive expansion that will launch somewhere in 2023 instead of 2022. But in this case 4th season would help to fill time. Also after all news Anduin looks like strong candidate for S3 boss (and obviously Jailer for S4).
People often forget WoD had so few patches not because they pulled resources after launch. We had rumors about WoD being two tier expac (Highmaul + BRF was tier 1) way before premiere. We will never know full picture, but most likely they tried (or were forced) to implement that stupid yearly expansions idea and at some point in 2014 WoD was redesgined to fit that format.