No matter how you structure BI, there will always be people who won't be getting it. If only citizens get it, then there will be lots of permanent residents who still need jobs, if citizens and permanent residents get it, then there will be lots of people of temporary work and student visas who still need a job etc. etc.
"Worst" case scenario. You end up having to import a bunch more foreigners to do those jobs at the lower wages.
"Worst" case scenario. You end up having to import a bunch more foreigners to do those jobs at the lower wages.