He wont concede, but it won't get to the supreme court either. His lawsuits have been little more than injunctions, and they have mostly failed through lack of evidence. He can't get the legal traction and it's clear he lacks the power base and support to try and steal it.
He will tell himself that he's been cheated, even if he can't prove it, because that's how he functions. It's his coping mechanism in the face of reality.
As I said, I won't be surprised to see the 25th come into play so a transition process can take place.