"We're not going anywhere."
I'd like another answer like. "We are thinking about providing a community version that one can deploy on its own servers, then we provide the IaaS when the customer might want to scale". If Parse had an opersource version to begin with, it would have been much much more successful and people would have been less worried about building on a third party platform.
If Firebase closes tomorrow there will be no migration strategy for people who built their infrastructure around Firebase.
> Firebase is very complementary to Google's other product offerings
Google is a big org. Tomorrow some upper executive you don't even know might decide your product doesn't add value anymore. You know that.