>When they do, it'll cause rent to drop in San Fran, NYC, DC and Seattle.
No it won't, no more than today.
>With basic income you no longer have to live where the jobs are and can move around freely.
Poor people are already "free" to not live in places they can't afford, and instead live in places with poor access to education and healthcare and jobs, and as such have reduced life expectancy. Your plan to use UBI to re-locate and segregate poor is no improvement compared to the current situation.