These things tend to rise and fall with history.
Jackson was popular for a long time, even put on the money. But now they don't even want his name on the annual fund raising parties.
Grant was beloved when he left office, and when he died. But now he's considered one of the worst.
Jefferson was adored for years, but lately has taken a beating over his slave ownership.
Wilson was admired for decades as well, but has lately taken some hits because of the failure of the League of Nations and his racist actions.
Even Kennedy has seen a decline in his reputation, mostly from his personal behavior and because of the uncertainty about is connection to the Vietnam war. Bit unfair too because he died before much of his work could come to fruition.
Obama will always "rank" as one of the more significant presidents merely because of his race. If the ACA survives after his administration to any significant extent, that too may carry him for a while. It will take decades to sort out his accomplishments, or lack thereof, with foreign policy.
But the tell all books haven't started to really come out yet, and there is back room talk about arrogance and mistakes that we'll only find out about in another decade or so. As someone else suggested too, his work AFTER his presidency may have as much influence on his reputation as anything he did while IN office.
And in the end it doesn't matter because either WE move forward or we don't. All of this is just about whether we'll assign blame, credit or just forget all about him.