Obama would be acting outside of the law, and Obama HAS DONE THAT NOW with creating his own selective deportation standards, and claiming it is his authority under discretionary enforcement.
Allow illegal aliens to remain in the country, is granting them legal status, ... to "legally stay in the country", as well as benefits. Amnesty is irrelevant to the actual reward of citizenship, but in fact eventually tied to that eventual reward, if you can call the wholesale application of citizenship to mass lawless persons that disregard our laws and sovereignty, as any sort of "reward".
What it is, is a wholesale abrogation of federal responsibility, where the federal government has no actual constitutional authority over immigration, but fails to exercise its falsely claimed authority, while denying that legitimate authority and real interest to the states, is a gross violation of the Constitution in and of itself.
Those "triggers" themselves are a joke, and each subject to discretion and corruption, and intentionally written to be corrupted.
We should commence deportation now, along with the wall construction and other border security implementation, and then, and only then, begin to discuss what adjustments immigration law might need. But it certainly would not involve any enormous thorough restructuring resulting in a 2,000 page bill.
The real underlying cause of all this insanity, utter perversion, from our federal government is the fact that the solvency of the dollar, and the American economy itself, involves an enormous Ponzi scheme due to the debt-based nature of the economy requiring the continual influx of more people and more debt.