It would be great to have an option to create special classes that are only available for players for a limited time. For example, it be cool to create Halloween class variants that players can only start every year or so. They could continue with that class through the whole game assuming the player doesn’t quit, but the class would only ever be available to start at select times.
The same idea could apply to abilities. I’d love to make “early adopter” abilities and such for certain classes, but as soon as I remove an ability from a class, it instantly removes it from every player that obtained the ability. The option to leave players with removed classes/abilities would create a lot of variation throughout the map, and further allow players in each game to feel distinct from another.