Let's talk logistics for minute.
Let's say that the low number is correct and we have 20M illegals.
ICE picked up a record of around 2300 yesterday
Let's say that an equal number are self deporting (but that's a wild guess)
4600/day x 365= 1.7M
That's 11 years EVEN IF this pace can be maintained.
The ONLY reasonable way forward is to allow companies to sponsor foreign workers in the same way that universities are allowed to sponsor foreign students.
Over a period of years we can cycle out the illegals and cycle in the legal labor that we need.
The right incentives will make all the difference.
The President has, rightly, started with the hard case criminals while incentivizing others to leave. In time, a new and proper immigration system can be formed that will help us find equilibrium. With alien crime down drastically, I think that most Americans will find this much more palatable.