AFK levelling is going to go away. It's just a matter of how it's going to happen. Arguing that it should stay is futile. It won't.
Only real discussion is how far they'll let players take breaks and still progress. None, 2 minutes, 5 minutes, 15 minutes? 1 mob, 2 mobs, 5 mobs?

I think it's reasonable to let a player autofollow for 5 mobs during a party if they have to take a 5 minute break to do something, or even 10 minutes. But not more than 30 minutes.

They could implement the system I proposed, which is if you don't generate any enmity for 3 fights, you stop getting sp until you perform an action.

Or they could re-implement the surplus system and apply it to afk levelling. Only give you so many sp per week that you can get while not contributing to the kill. Maybe 5k sp a week max that you can get while not doing anything for an entire fight.

That's a more complex system, but more flexible.