I dont think the US can afford to search everyone out to kick them out. They will be even more in debt by a large amount. Think about the money it will take to find one person as probably triple or even quadruple the amount they would charge for a fine to legalize (i would imagine).
Also its true, immigration reform would probably take away a lot of jobs. But again, thats not their faults. I know of many people (including myself not to sound pretentious) without status who are a lot smarter than above average students in this country. I don't doubt that a lot of us will be taking away jobs. But then again you see half the kids who dropped out of your high schools for drugs and gang purposes, are just a waste of space here. There better off swapping places with us, a lot of them end up in jail anyways which is the unfortunate fate of a lot of undocumented people living here.
But anyways, thats why i believe it would be best if the healthcare reform bill showed positive signs (this will show that the bills being proposed are not disasters) and that new jobs are implemented so it shows that there is a need for more workers.