Well, if everyone is unemployed there won't be much of a market for these newly AI enabled companies to sell into. Also, in the extreme, you'd have deflation such that it's worth hiring again. This would be very painful.

More likely automatic stabilizers and additional stimulative spending would have to happen in order to fully utilize all the new productive capacity (or reduce it, as people start to work less). It's politically hard to sustain double digit unemployment, and ultimately the government can always spend enough or cut enough taxes to get everyone employed or get enough people to leave the labor force.