Whenever there is a Firebase announcement there are many replies along the lines of "this won't work for me because it's owned by Google, may be discontinued, doesn't have on-premise solution, etc". If these are your thoughts then you are missing the point of Firebase. It enables small web development shops like mine to focus on building beautiful web applications without having to give up manpower toward backend engineering. The cost of using Firebase is peanuts compared to the savings in employee hours.
Perhaps some day we will have to migrate elsewhere, but I find that possibility extremely unlikely because the clear amount of effort it took to create the Google-y version means this is a long-term play.