Eventually, the only occupation would be a “solider” when governments force conscription on everyone that can’t escape in the next war that gets created.
work is non optional, even nialistic,narcisists got to get up and husstle to get the attention they desperatly need for survival, and mostly everybody else just likes doing and building anyway, so by work then perhaps what is implied is "work for", but then the question becomes, will paying for stuff then stop?, or will be doing without, and "work optional" become the fancy new label for slave
I'd read Musk's message closer to "In 10 to 20 years, AI will make the working classes optional, from a tech billionaire's PoV. Proles should expect lots of pie-in-sky promises, right up 'till the Day of the Downsizing."
The absence of preoccupation with work will be a boon for destabilizing geological forces. A work-free society will have its own challenges. Bad art might be the most dominant one, if we’re lucky.
This idea, also espoused by Star Trek, is a curious one.
The idea of abundance leading to anyone can have anything they need or desire simply does not track.