From a business perspective this probably won't hurt Reddit much if at all in the short/mid term. Enough power users will stay, meaning that content will still get posted, meaning that regular accounts (lurkers+dispassionate users) would be happy enough, meaning traffic won't nosedive.
Plus, there won't be as many people pointing out bots, so reposts and stolen comments will keep engagement numbers up as well.
From the perspective of people who actually care about the Reddit community, though, things may get really ugly. The quality of content and interaction will be hurt, possibly (hopefully?🤞) irreparably.