A blockchain has certainly some good features that can be used in distributing money as well as handle identities. If this would be an implementation as how crypto is implemented today, de-coupled from fiat, no control, volatile, I wonder. Although I really would like to see crypto getting mature, and was hoping for a much shorter maturity adoption rate as so many other technologies; I start doubting this fact. Crypto to reach maturity may take another 1 or 2 decades. UBI we need sooner. Hence I believe, UBI will be implemented in different ways, using fiat, maybe powered by blockchain, but this could be a private one, or semi-private/public version; But I don't see Bitcoin or any of the altcoins playing a role anytime soon.
Added to that: It seems the fast majority trusts our financial institutions; They trust identity services used left and right by digital services; And the governments have identity information of its citizens. Hence distribution of UBI is as simple as the governments are distributing unemployments benefits today.