The way I see it there are 2 paths forward for Lemmy. Without at least one of these scenarios occuring it seems unlikely that we'll get back to a level of natural growth.

1. Reddit starts fucking up again. If this happens it'll probably be because of or sometime around the IPO so be on the lookout for that.
2. We start getting significant user growth from other fediverse platforms, likely Mastodon. These users already understand how federation works and are actively looking for a lot of the features that Lemmy has to offer on their existing platforms. I think the way to get there is primarily through topic dedicated instances springing up as professional groups find Mastodon does not truly fit their needs. One recent example of this is links.esq.social which is a brand new currently unfederated instance for lawyers and legal professionals.