Like i said to me it's an economical decision. I believe the border should be closed off and policed more vigorously. But for those in America now? If we can come out better off by taxing them and making them residents than by expelling them, perhaps we can use that revenue for enforcement of the border. We all know it's going to be a huge ongoing cost to build, maintain and enforce it. I'm not against that but i also think maybe we should do something like this -
Tell all illegals that have 6 months to leave or register with the government for a residency status. Once you have this you will be under a probation period for 5 years. During that period you are not eligible for any government assistance or welfare. You must pay taxes on all income and can/will be deported if you are found to be lying or found guilty of a felony. Like American citizens you must buy health insurance (or have an employer who does) for your whole family, if you do not you will be deported.
After those 5 years you must prove you have contributed to American society and have ingrained yourself into the American way of life, whether by learning the language and/or customs of Americans, volunteering etc. You must also prove you have worked for at least 3 of those 5 years.
All revenue from taxes collected will go towards enforcement of these guidelines and enforcement of the new border policies.