Relatively new Firebase user here, so take this with a grain of salt.
By itself, I don't think Firebase is the right tool for BI/Big Data. Firebase seems like a great production data store because of it's speed, scaleability, etc., but those are production concerns. BI concerns tend to be a bit different; you often want to collect huge amounts of stateful data, then map-reduce it. That's a rather different problem.
I
think the solution is to integrate your Firebase with a BI/DW tool like
Amazon Elastic Map Reduce or
Google's Hadoop on CCE. It should be possible to set up a custom server to stream updates from Firebase to your Hadoop cluster. When the Hadoop jobs finish, you could push data back into Firebase in order to provide the application with a consistent API for data retrieval.
That was all pretty hand-wavy, but long story short I don't think Firebase alone will solve the problem.
Cheers,
Simeon