As Basic Income is being introduced, unions will be slowly sunsetted. They may still be useful to oversee work quality and workers' rights, but movement to BI means at-will employment and that's not something they'll get to haggle with.
The idea of BI is that you won't be able to live off it in Montreal. It might be sufficient to live off in some small remote town, but not in megapolis. They'll have to still wait tables, or move from Montreal.
Government unions are the most powerful organizations in the world, they will not 'sunsetted'. They have been growing in numbers, dollars and power for a 100 years, it's not going to stop now.
The idea of BI is that you won't be able to live off it in Montreal. It might be sufficient to live off in some small remote town, but not in megapolis. They'll have to still wait tables, or move from Montreal.