I would love, if there was a standalone client to purchase, that would feel like single player, that we could play without internet, but have to verify we've paid every week or month, depending how you want to do it .
Adjust to 1 person dungeons too, also adding dungeons to zones that currently don't have any atm , Azshara , etc.
if 1 person would be more difficult to do, how about letting have some NPC characters to help us with these dungeons, letting us control what spells they would use, which order of abilities to cast, what to do in various situations, who to prioritize, etc.