These are also great features. But what happens to that customer that one day realizes they need just "one more" feature - and that feature happens to require they start running their own enterprise?

Not trying to be overly critical here, what you've built is very enabling for a lot of app creators. But it seems to me that any really successful client of yours will eventually outgrow your feature set and need to migrate to a custom solution.

At that point I don't know how you hold on to those customers without needing to build something like a Heroku.