The problem is there are changes that would be extremely good for Classic, and a lot that would be terrible. But that line is different for each player.
Like for me I would love for them to rebalance all of the specs/classes. Make new Classic raids, new battlegrounds. Essentially restarting WoW from the beginning. But some people just want base classic/BC.
Some want dungeon finders, some want tokens (You’re clinically insane if you want this). It just depends who you ask.
Adding in store mounts and paid character boosts are awful additions and ruined the integrity of classic for a lot of people. It’s one of the primary things I hear about as to why people aren’t willing to put the time in anymore. On top of the obvious recent problems that have come out.