I believe NASA ultimately had to scrap the idea, but the cloud 9 buoyant cities idea is an old one, tracing back to Bucky Fuller and Earth, and it’s vastly more plausible than trying to make Mars habitable. Or even the Moon! Venus has Earthlike conditions if you exploit buoyancy to settle in the goldilocks area of the atmosphere.
Not enough to achieve something, but enough to pretend that it might do something.