Yeah, I'm certainly not going to delete my Reddit account immediately. When Digg was fucking up, it took several rounds and I really made sure I was going to be comfortable on Reddit before I deleted my account there. But once critical mass was achieved, there were major threads on Digg that became literal ghost towns of deleted account comments pretty quickly. It was obvious what was happening. I don't expect we're going to see quite the same massive collapse at Reddit unless they follow up this API decision with killing old.reddit in a month and then dropping all NSFW communities in another month. If they do those things, Reddit is going to essentially die.
I'm waiting for a strategic moment to pull out. If they don't address the concerns of the user base and the moderators, after the protest, I'll delete my account. I've been on Lemmy for a while but it really lacked users. So post Reddit it'll either be Lemmy of nothing.