If it was more cost effective, that would happen already. Produce prices will likely rise if this becomes an issue.
Similar to how people buy Chinese manufactured products in Wal-Mart then complain about manufacturing being overseas.
* consumers would be paying a fair price with rational decision-making
* there would be "made in the usa" marketing for local / national produce
* voters would look much more carefully at minimum wage increases
Of course this is all speculation on my part.