Your 401k comment gave me an idea for one potential tweak that would make a big difference. If there were a plan to collect a small yet reasonable tax over the course of, say, 10 years or so, to build up an initial pool to draw from, then it might be able to generate enough interest to sustain a continuous payout. Once payouts have started the initial tax might be relaxed or eliminated, though it would depend largely on population growth and how quickly the pool compounds.