The game would have to seriously go very far downhill for players to fondly think about BfA.
The difference with MoP and WoD was what people disliked about it and it being something easily overlooked over time.
MoP was mostly thematic hate, not the actual gameplay and design systems. It was all about the “joke expansion”.
WoD was hated mostly due to its terrible release schedule resulting in many months of simply no content, along with being the first time classes truly got pruned.
The actual game systems in WoD though weren’t really that bad, there was just nothing to do.
BfA has made terrible design choices that affect tbe game on a systems level which is where the big issue is.
Not only are the classes less fun to play, but there is so much “required” content that provide ridiculous power to your character yet don’t feel rewarding. On top of that, 90% of that content is the same content release in 8.0 and has been required since release.
I would love to see a WQ statistic for a player who has persisted through BfA. It would be interesting to see how many times a single WQ has been completed over the duration, I imagine the results would be shocking.