Infinite demand, maybe, but not at wages that most people are willing to accept. Of course, if there's literally no other work, then previously-middle-class people will take what's available and become homeless because the wage doesn't pay the bills (which are, in places, extremely inflated due to decades of jaw-droppingly bad housing and transport policies). Sounds like a highly desirable future.

Yes, but thanks to Baumol's cost disease productivity increases in other sectors can have spillover effects in terms of wages.

That assumes the current high wages are here to stay. This seems unlikely if AI consumes most white collar jobs.