It has been a long time since I looked at it, but didn't the Steem/Steemit white paper also hint at something similar? Dan (and his dad) seem quite interested in exploring the idea of Basic Income.
I notice you mentioned @mannacurrency; seems to me they have a golden opportunity to create some synergy with Steemit... allow people to easily convert any Steem they wish to Manna. They already have an account here; a lot of smaller Steemians don't make enough to warrant withdrawals... but I could see how allowing people to just convert their 3, 5, 10 Steem to Manna could be a great lift to the Manna project.
But maybe I am missing something?
Bright Blessings!