They said during Blizzcon that most of the legwork has been done with Classic and that they're generally open to the idea.
The only thing that really came out ahead was DM.
The honor system was released like ~3 months after release, which is completely fine.
BG's came out earlier to save what little faction balance was left on the servers (and to push out some content before the holidays is generally a smart move).
Aside from that, it took them almost 6 months to release BWL, having to wait like half a year for a new raid is retail level of release schedule.
If they would continue with that pace, we wouldn't have Naxx until mid 2021.
Heck, BWL was most likely even delayed to avoid significant overlap with 8.3, it only makes sense now to push out content quicker.