A few more points on top of these:
(1) The way jobs are valued would fundamentally change. Rather than higher wage work being the work that fewer people can do, you would also see a rise in cost for jobs that people do not want to do. Today you have your unskilled employees trapped between a rock and a hard place when you offer them a job as a burger flipper - work in wage servitude for us, or starve. The employer has a tremendous amount of sway during negotiations in an economy where employment is effectively mandated to survive.
Ask yourself - "why is McDonalds so cheap?" does it make any sense that having people working in depressing service jobs makes cheap food? Wouldn't the optimization of food be automated delivery, minimizing the people involved? McDonalds can only exist as it does today because all its employees are forced to work for it.
(2) You would also see production shift. Economics goes where the money is - we have too little low income housing and too many McMansions because single family houses are profitable and reliable when sold and low income housing is unreliable and less profitable. If everyone had a minimum of income, there would be a tremendous amount of economic pressure to meet the demands of that crowd that has maximal economic consistency in revenue. So in the short term prices would be a mess, but in the long term the equilibrium state would be that there would be a huge market to provide as much of what the UBI unemployed class wants as possible within their budget for profit.