Proving the concept is huge, since this is an idea that's at least as old as satellites. Once they have the proof of concept, I see three additional hurdles: 1. Safety. Prove you can keep these things in the air for months at a time without any of them crashing. 2. Payload. Exactly what you point out. 3. Operational usefulness. Can this thing stay in the air for months while flying the routes necessary to complete its mission?

I really hope Airbus and others are able to make this concept work. It would be nice to have an in-between option between UAS and satellite.