Every time a patch is announced for retail we see a rash of “Classic is dying” posts. They cite lower activity on their server, or no more que times, or daylight savings time, or whatever.
Here is what people don’t get.
Everything you invest in classic is effectively banked forever. When you come back for P2, or P5, or ten years after P6 this server will still be here. Your gear will still be exactly as powerful as it is right now. Your character will be right where you left them.
Many, many people ground out their first level 60 knowing they’d burn out. They knew they’d take a break, and why shouldn’t they? If they’re in the spot they want to be they can actually take time off without being penalized.
In retail taking a break puts you behind, at least until the next tier invalidates everything again. In Classic you keep what you earn. It stays relevant.
That’s why Classic will endure. There will always be people who want to pick up their hunter and wreck some dorks in Arathi Basin on a random Saturday, and they can come back and do exactly that without spending months grinding new gear.