Switching supermarkets is much, much, easier than switching backends. I'm sure lot more BaaS companies will pop up to grab former Parse customers. I'm not sure how many of those will still be around in another 5 years.

I strongly suspect there's something negative about the economics of BaaS services that's being implied by the fact that two of the most successful providers have shut down after acquisition.

That's exactly our thought (hasura.io) while we prepare for our "launch" next week. We've been studying Parse's growth and are definitely going after their market. Our core philosophy with the BaaS is however to keep it as open as possible. We wrote this up in response to Parse shutting down: https://news.ycombinator.com/item?id=10994104