When Marx hypothesized about "communist " society, he was postulating a FUTURISTIC world. And that is still an as yet unattained (though not unattainable) ideal.

Yes. Based on modern technology it's not only possible but inevitable
Hierarchies are necessary to establish pecking order, status, power relationships, and of course how the profits are distributed; the higher up, the more money.
When and if full automation is achieved and a large percentage of the population is freed from routine, repetitive labor, the non-working segment will be given a Basic Universal Allocation. This would be pro forma, to ensure rational
distribution of goods and services. Money itself would be eliminated from circulation.
The working segment will be given additional benefits, status, etc., so it won't (at first) be pure communism, but it'll be close.