I keep thinking about post-content after naxx is out and what they're going to do. I still feel like expanding into TBC and wotlk would be a mistake instead of branching off into its own game. I just personally don't feel like going down the expansion route is worth it because where do you end it? WOTLK introduced LFG and phasing (granted it was limited phasing with quest areas, etc). Sure it had the most memorable raids and whatnot cause Arthas OP but WOTLK introduced everything that eventually lead wow to what it is now.
I unironically want a 1.13 and I want them to introduce tier sets for stupid ass specs, like arcane mage or spriest, etc
Well let's assume Classic last for 1.5/2 years of time. Even if they went TBC and Wrath after that's about 5-6 years of Cash Cow Milking they can do. Without needing to add anything new at all just open up some new servers and gate them over a 1-2 year period each. If by 2025 they haven't come out with WoW2 or a meaningful reason to play the retail version they should just close shop.