There would never be a plan. The system did not plan on getting where it is, and it would not get out.
The best thing the government could do is provided visibility into the policies i.e. 'we're going to require $X min wage on this date, and $Y on this date, and after 20XX we're going to be checking on businesses, starting with fines in the first 6 months, and then more serious.
The system would have to adapt - and it absolutely could.
There is some possibility it would happen in that the notion of providing a 'living wage' to everyone would be popular, and it could by virtue of a Supreme Court ruling for example be extended to everyone. It would be then up to the government to theoretically enforce wages and standards for non-citizens, it comes down to the political will - plus - there will be millions pushing for it, thinking about their own personal gain, not necessarily piecing together the likelihood of keeping their jobs. I bet most undocumented workers, once they find out they are legally entitled to a bunch of things, and would have the protection of the justice system ... would push for their ostensible rights.
It would be a pragmatic solution to the 'gaping hole' in the economy, civility, lawlessness and solve a lot of problems at once.
Instead of ICE kicking out illegals, they turn on their head and start enforcing labour laws ... which paradoxically has a much more powerful effect on the border.
But yeah, very unlikely.