This, I think, is the cause of most of the misconceptions when it comes to Classic: let’s assume that Classic will just go the way BfA (and every expac before it) went and draw a raid-or-die crowd that will consume all raids, including Naxx (which is kinda adorable, given what I’ve heard about how difficult Naxx is when you’re limited to level 60 gear, even BiS in every slot), within a short period of time.
Everyone, not just 0.1% of the playerbase, will obviously “have Naxx on farm,” because what else is there to do in WoW except raid? Also, why on earth would you ever farm Naxx if your ilvl isn’t always going up, making other content trivial and turning the drops coming from your most-proud raiding moments into vendor trash or enchanting mats?
What people need to come to grips with is that this game is not just for PvE raiders. If that’s all you’re here for, there probably isn’t a lifespan of this game that exceeds about 1-2 years before you get bored and quit.
What surprises me is that pservers still seem to hold a crowd for a long time. I have no idea about the numbers, have never actually been to a pserver myself, but recently found out that there are people out there who actually make IRL money farming and selling gold to players on pservers. It just floored me, that there are legitimate business models available for a derivative-of-a-derivative business.
In any case, it might be interesting to ask the pserver folks what they did that kept them in game after they had “Naxx on farm” for a decade, and what holds their attention in a game that doesn’t relentlessly progress forward by trivializing all of your gear and all of the content you can still play at level 60 with full BiS equipped.