There's not a chance in hell that will happen. It doesn't matter if the SCOTUS is activist or not. The 22nd amendment spells it out clearly. He can't be elected for a third time. Here's the text of the amendment:
No person shall be elected to the office of the President more than twice, and no person who has held the office of President, or acted as President, for more than two years of a term to which some other person was elected President shall be elected to the office of the President more than once. But this article shall not apply to any person holding the office of President when this article was proposed by the Congress, and shall not prevent any person who may be holding the office of President, or acting as President, during the term within which this article becomes operative from holding the office of President or acting as President during the remainder of such term.
What are they going to do, say that "twice" doesn't mean two? He was legally elected... twice. Two terms.
Twice. I get it, people think they're being edgy and funny by stirring up the tinfoil pot. But it's not gonna happen. Like someone else mentioned, at least half of the states wouldn't even allow him on the ballot. Without those states it is a statistical impossibility to win the electoral college vote. Sure there are a couple of loopholes, but they're so far out there that if he attempted to exploit him the public outcry would force him out of office via Congress. Obama isn't even that popular anyways, lol. The Democrats want to win, not try some crazy shit that's never been done before. Hillary is a much safer option for them.