The "legacy thing" may be harder than Barack Obama imagines.
Beginning his second term, Obama has a focused, though unstated, agenda: to achieve presidential greatness in the eyes of historians and Americans. In this, he will almost certainly fail. He is already a historic president as the first African-American to be elected, but there is a chasm between being historic and being great.
Presidents are ultimately judged not by their total record, or by their ability to enact their agendas, or by their popularity. They are judged by whether they get a few very big decisions right or wrong.