I think Obama would like to change the legal status on his own. But he can’t. All he can do is use his authority as the head of the executive branch of government to tell the USCIS (formerly called the INS) not to bother with certain cases.
Besides, look at this from the perspective of Manuel Labor who is here illegally. He knows that once he registers with the immigration authorities to take advantage of this offer, they can keep the record indefinitely. He also knows that in January 2017 Obama will be out of office and whoever replaces him will be able to order the USCIS to access these records, find him, and put him on a bus to Mexico.
Manuel Labor isn’t stupid, he’s been in the US for five years and he knows how to get by and work under the table. I don’t think he’ll take this deal. It isn’t a good one.