Not happening. I don't believe there is any chance in the world of Obama seizing power for even a few minutes beyond noon, January 20, 2017. Obama will leave voluntarily and as scheduled. There are a hundred million armed Americans, most of whom despise Obama. Many of them are Secret Service agents. We don't have to worry about actual violence on either side because Obama is a big sissy who would never endanger his delicate snowflake self. Barack the First has no choice but to follow that one part of the Constitution he despises, and he knows it.
Obama is going to be in Cuba and South America yukking it up with his communist/terrorist buddies in November and December. If an EMP hits here he’ll be fine. Look for a Thanksgiving vacation where the girls (and maybe Michelle) are down in South America with him. Or they’d probably be OK even if they were in DC now that they’ve got a nice bunker under the White House with medical supplies to last them years.
If you looked in one of the links I posted you’ll see that we’ve got military supplies/command in CO where it’s naturally protected from EMP effects. So Obama would have his military to enforce martial law. If the hit was in eastern US there would be large cities with no power and there would be chaos. In that scenario whoever has the physical power to subdue everybody else would be the ruler. And Obama would have his military yes-men (since everybody else has been purged from the leadership) to do whatever he wanted.
What would stop him, in the face of an EMP attack BEFORE his 2nd term expires?