This is exactly how it's gonna play out: (1) secure the borders; (2) 'legalize' illegals already here through a guest worker visa to get them paying into the system; (3) set up an ongoing guest worker program.
Once it's not illegal to hire an illegal, but illegal not to pay into the tax witholding system, you'll see businesses fall into line. The tax man has a lot more power than the police, and it ain't go nothing to do with legal status - it's all about compliance.
An aside - the number of illegals currently here amounts to 10 million (conservatively), this will multiply to 30 or 40 million within 10 years - not counting additional illegal immigration during that same period. Perhaps as much as 15% increase in our population within a decade as a consequence.
Good or bad, this needs to be considered at the same time as the president's plan.