What I wrote is based on my personal experience building a commercial app which I am submitting to the AppStore this week.
After >500 hours of work over six months.
I don't think we are screwed. There's risks, but it is also highly likely that living standard will go up for everyone and working time down dramatically.
Yes. If AI doesn't slow down soon, there will no longer be need to build most software. This is not the case yet, and in my opinion we are now at at great time for building new products.
Why would I hire Alice to work for 4 days a week when Bob is willing to work for 5 at the same price (assuming both are equally productive, even if AI has made that productivity extremely high)? So long as there is an oversupply of qualified workers, I doubt working hours will change. To do so would require social contract changes like for the standard 40-hour work week.