The data isn't reactively loaded in realtime, but Meteor itself is still reactive. What I mean to point out is that even if you're depending on say classic JSON

The data isn't reactively loaded in realtime, but Meteor itself is still reactive. What I mean to point out is that even if you're depending on say classic JSON APIs, the meteor app within itself can still do reactive-features (templates, local collections, etc). And depending how you implement things, you could still take advantage of push capabilities for your data from a legacy endpoint. But yes, I agree, it's not ideal until a SQL adapter is available.