I would say it is sustainable IF it's rolled out properly, if you are only just barely given enough to survive, your not going to take risks for creatiivities sake and end up going back to a grind of some sort to get that slightly more sustainable odds. The real big problem is how do we deal with the jobs that can't be automated? How does society react to after spending decades training in order to specialize in something so they can survive cope with others who can now thrive without it? Do we see massive unemployment from critical organizations/companies as workers decide to indulge in their passions on UBI instead of slave away for a sustainable living? Do we need to wait until all jobs can be automated before this is even possible, or does the society we have today collaspe? These are some of the actual difficulties with rolling out UBI and a proper solution has to address them for them to be sustainable. As it sits I don't know if we even are at a level to do much, most ai would be good for say being a CEO or high level executive looking at trends and creating a curve essentially to fit the data points those trends are creating. But how would people react to CEOs getting obsoleted and collecting UBI with their golden parachutes still? Probably pretty damn fucking badly, calling for UBI to be abolished or some shit and you wouldn't see much resistance as the share holders can eventually reap in the profits when we created precedent for no UBI related to jobs that AI/automation took over. So you need protections there first but our governments are reactive and not proactive. Sure maybe an authoritarian regime could enforce it but now you have to hope you have a benevolent dictator, which is pretty much an oxymoron, and they would need the foresight to leave democracy in there absence. Not to mention that force would need to be a global government or other economies still based on capitalism ideals without UBI are going to take advantage of their position leading to unsustainablity and eventual collaspe. We have a lot of fucking work a head of us but if you were to compare hunter gathers to today's societies and advancements it would almost seem impossible. I don't expect UBI or full on automation to make it into our societies without some sort of societal collaspe first that allows us to rebuild with the understandings of our current systems failures clearly documented. I think we are many generations off from that rebuilt society even if we bear witness to our societies collapse in the upcoming generations. But I agree it would signify a huge advancement in humanity and probably give us the foundations to truly become a type 1 civilization and set the stages for possible advancements to a type 2 civilization. But we are not there yet, unfortunately.