Gave people lots of health care / ACA (combined): If it doesn't crash and burn under it's own weight, it'll be remembered well. If it does crash and burn, then no. It'll take at least 10 years for this one to shake out before we can know.
Shifted thought to the left: Presuming that is good, how did HE do that?
Gay marriage: Again, how did HE do that? It just happened on his watch. He does get kudos for ending DADT, though.
Out of Iraq/Afghanistan: Are we, really? Plus, did he leave too soon? How's that working out? Seems more of a mess than before, especially Iraq. Not something to brag about, unless half-truths and lying-by-omission are the strategy here.
Unemployment down: Government has less influence in this than we like to think. Much of it is part of the upswing of the natural cycle, but sure, the sitting president gets the credit when it goes well and the blame when it goes downhill... regardless whether they actually earned said credit or blame.
He's been a caretaker president more than anything else.
Huntsman / Kasich 2020
Then: "Any child can grow up to be President."
Now: "Any child can be President."