Re: Possibly a sensible solution
I agree that this is potentially a solution, but some of what you have written is really not right.
Cheap - long term this is unlikely to be cheaper than a dedicated satellite. You need at least 3 aircraft (1 in flight, 1 in refit/maintenance, 1 spare (in case maintenance runs long)), you need to conduct regular maintenance of them (easily the most expensive part of any aircraft's life cycle), you need to constantly fuel them. A Satellite needs to launch once. It's an expensive launch, but that's it. Only ongoing cost is maintaining station, which means a small amount of time connected to a ground station. Significantly cheaper than an aircraft. So over the lifetime of the product, I'd guess they come out about the same. Admittedly, I'm talking about a proper Telcom satellite, not a Starlink swarm of satellites, which admittedly, they get expensive fast due to needing a dedicated ground station (or multiple stations) and lots of launches!
Solar Powered - they've already said hydrogen powered. Hydrogen can be produced cleanly, but generally it's not. It's usually made from cracking fossil fuels, as that's easier and cheaper, than Hydrolysis. Hopefully, that changes in the future, but I wouldnt bet on it.
Does not clutter up space with cube-sats - Telcom sats are not cube-sats, they tend to be big old things that sit in a Geo-sync orbit. The reason being, you want them sitting above the spot of land you want them monitoring. Put them in any other type of orbit, and they have to, well, orbit the Earth, so they'll be moving off station regularly. That's why the likes of Starlink need vast swarms in order to cover the whole sky effectively. And to piss off the Astronomers, of course...
Enviromental Impact, would be interesting to see. A single Rocket launch versus continually burning low levels of hydrogen for months on end. I'd almost suspect that the launch if done with a standard LOx/LH2 Rocket would be less environmentally damaging (as the output is mainly water vapour). Kerosene rockets, would be closer.
As for your lower altitude possibly being more vulnerable disadvantage. There's no "possibly" about it. Atmospheric winds are not something to sneeze at. Even in relatively benign areas, they arent exactly friendly. In Space, your main issue is Cosmic Rays, and those can be relatively well accounted for through hardening, and data monitoring.
For me, probably the biggest advantage of the A/C version is that, it is childs play to upgrade them. Once you launch a satellite, it's there and it's done. If the tech upgrades or changes a year down the line, too bad. An A/C system like this can upgrade by simply swapping out the modules. That massively extends the life of the project...