I visited Arcosanti in 2014. On one side, amazing place. On the other, it's a failed project. Soleri stated that it can only be self-sustaining when it reaches 5,000 people. I think it never went above 200, and it's now below 100.
The story is complex, but my understanding is that the main failure point was the local officials not wanting Arcosanti to exist and putting up regulatory barriers.
It's worth noting that Soleri ran the project as a benevolent dictator, and when he fell into the poor health of old age most decisions stopped. He's recently past and left behind a bit of a power vacuum and the other people involved are reorganizing to deal with that. Coming out the other side of that reorg is an opportunity for change and it's too early to assume Arcosanti will stay in it's current form.
They are basically blocked by money. If they could get enough money to pave the road to the property they could get building permits again. They need either a rich benefactor or a group of people interested in buying into the concept (and the leadership capacity to manage that).
They've done a commendable job of trying to keep up with some modern advancements since the original designs were inked in the 60's. They have fiber optic internet access, some solar panels, and a few ADA-compliant ramps. My concerns would be more about integrity of the foundations. Modern surveying, concrete chemistry, and so on have raised the bar. I think there may have also been problems with routing utility lines with ventilation shafts and not having much of an alternative due to the structures being solid, load-bearing concrete.
As an organization, I don't have very much faith in the leadership doing much more than barely staying afloat. There's a strong bias for seniority over meritocracy, which over the long term frustrates and deflects talented people with good ideas and favors people who just stick around or have don't have better alternatives.
Upvoted for clearly knowing what you're talking about. :-)
I built some of those foundations, back in the early 90s. Not much to worry about there -- they're tied straight into the basalt bedrock. Concerns about the extensibility and adaptability of the construction are well-placed however.