It’s not a great plan, they break federal laws (which we know obviously aren’t enforced, but they’re federal laws nonetheless) by being here illegally. Why give felons a chance by being good little boys and girls?
The people that Trump is talking about are people who have been here for years and have been productive, some of whom have created businesses. In all cases they would be people who have assimilated and regard the U.S. as their country. They still have to return to their native countries and go through the process of legal immigration.
With the additional implementation of a reduction in overall legal immigration, this is a good plan.