"Required to return to their home" implies some form of enforcement. For instance, you are "required" to pay your federal income tax and if you don't you can be prosecuted for failing to do so. I assume that requiring them to return home if they are no longer employed (for they will be tracked via the guest worker visa) means that armed LEOs will hustle them along if they don't.
I could be wrong. We'll have to wait and see. Right now, the situation is that nobody cares whether they are working or not and nobody is forcing them home. The status quo can't stand. If the President's plan doesn't work we can always go to Plan B. Anything is better than no plan (what we have right now).
What planet are you living on? THEY'RE REQUIRED TO RETURN HOME UNDER EXISTING LAW, yet they're not doing it. What makes you think they'd return home under this new law?