One problem with these models
These model assume that the infinite productivity increase will be matched by an infinite consumption increase.
That is simply bollocks.
We are rapidly approaching a point where we produce more than the population can consume in most industries. At that point we have no choice, but to reduce production which in turn means reduce employment and/or working hours.
So, we have reduced them, now what? Two options:
1. Lay off the "this is not how capitalism works" the no longer needed workforce and get the mother of all winters of discontent.
2. Bread and circuses. Works in the short term (this is what the guaranteed pay is at the end of the day). We all know where it ended up for the Roman Empire.
Neither are sustainable - one is a short term disaster, the other one is long term disaster.
The reality is - an infinite productivity increase without providing a bread and circuses environment which is a killer in the long term mandates option 3:
3. Long term population growth control to match the actual labour demand.