There are many people from Niger living in Nigeria, many have lived in Lagos for donkey years and are so much at home. There're Malians too. I don't know about people from Burkina Faso sha. I haven't met a person from there.
If those countries are no longer members of ECOWAS, all their citizens living in ECOWAS countries should be made to provide their passports before they can be allowed to leave and work and do business in ECOWAS countries.
“African Union Expresses ‘Deep Regret’ Over Withdrawal Of Burkina Faso, Mali, Niger From ECOWAS - Channels Television”The African Union on Tuesday said it feels ′′deep regret′′ over the withdrawal of Burkina Faso, Mali aNd nIger from ECOWAS.