Our general philosophy going forward is that we want to minimize, or ideally even eliminate reliance on third party online services (that might disappear or not be available in certain countries or might be overtaken by competitors or just work less well for you than a competitor) in the core SDK. We want the the core SDK to become a universal standard.
That said, we know there are tons of libraries like Realm and others that people really want to use, and so we’re looking at different ways to make it possible to use as many of them as possible – without having to wait for the Expo team to add support to the core. We’re working on something promising now but its not ready yet. Stay tuned.