I think there's maybe a 9% chance Trump will ever concede.

If he does it'll be extraordinarily bitter, contemptuous and venomous, and full of denial that he actually lost.

But more likely, he will never, ever admit he lost. I mean: ever...

Even if he (unlikely) concedes, the next day he'll return to his conspiracy theories like concession never happened.

When his court cases fail he'll blame the judiciary. He'll claim they're all in on a hoax, and try to cause as much damage to them as he has to democracy...

He won't help in the transition. In fact he'll do everything he can to undermine it, and try to de-legitimise it. He'll dog-whistle to his fanatics that there was a coup. He'll certainly indirectly suggest they overthrow Biden, but maybe even say it directly...

He'll be racist about Harris. He'll say Biden has alzheimers. He'll say they should all be in jail. He'll demand the military steps in. He'll blame Obama and Clinton, and he'll promote QAnon. I'm pretty sure he'll start organising rallies again, cos he needs the empty approval...

He won't attend the inauguration, and will most likely hold his own rally to coincide. He'll most likely encourage violent protest at the inauguration.

And he won't stop. I mean, not ever. He'll be a daily hand-grenade in the public square until he dies.