Like many utopias, it is the how you get there that is the issue.
I would venture to say we could have had a post-scarcity economy ever since 1920s or so (plus or minus a few decades) . I would suggest communism became a reality precisely because people could see that we could organize society and create adequate production and distribution for all.
The hard part is getting there.
As long as there is a single human job that needs doing, it will be hard to get there.
As long as you need people to do jobs that are not of their interest, it will be hard to get there.
This is a big one. It is relatively easy to imagine a world of people doing things out of their interest if you're an academic or doing something you love. It is much harder when you think of jobs you'd rather not do.
Even something like a doctor, which would be a job that might exist just out of interest. You'd have to ask, if you'd want to be that doctor working the 3 AM midnight shift in the ER instead of lounging off the state?
Already in the Western world, we have the mentality that some jobs should be done by immigrants or overseas? We don't want to work our own farms, take care of our own elderly in old homes...
Already we have issues with labor unions wanting a better standard of living than the rest. We have rich people who want to keep more of their money. Already we have homelessness. We have people who demand more of the state than the state can afford. We have monetary issues...
I'm not saying some government won't come up with way of solving this. I'm just saying, it is the how we get there that is the hard part. We'd had the technical means for quite some time.