Building your business on the back of somebody else's API is always gonna be a risky endeavor. Luckily, Apollo is a great client with loyal users, so hopefully Christian can spin off his own backend forum and build from there. Reddit's been making some dubious moves (crypto avatar-things, hostile dark patterns steering mobile web users to their app, more ads, etc) that I wouldn't be surprised if more and more users went looking for an alternative with a similar flavor.