This might be a nitpick, but I want to get the motivation right before commenting. The phrase “scorched earth” implies an irresistable urge for retribution. Trump isn’t above retribution, but I don’t think it’s a major motivator for him. All he wants is to preserve and/or expand his wealth and popularity. He will do literally anything he thinks he can get away with to further this aim.
To put it another way, if Trump starts smashing stuff, it will be an attempt to either manipulate the vote count, or cause uncertainty in it, or distract from inconvenient news stories. That’s not terribly reassuring, but it is at least a constraint. He was never going to start a nuclear war as I initially thought. He can’t abide the thought of him or his precious hotels coming to harm.
I’ll also put out there that Trump doesn’t have grand strategies. He has grudges, habits, and impulses. I’m sure somebody close to him does have an 11-D chess strategy involving some unsavory election-winning tactics, and I’m sure they brief him on it, but I doubt Trump has the intelligence or interest to adopt most of it. Who knows, maybe there’s an adult or two remaining in the room, or one of the interns came of age in the past 4 years.
I think what we can expect to see is more of what he’s already been doing. Stochastic calls for violence, casting it as a conflict between red/blue, black/white, police/the Antifas, inciting people to vote illegally, to intimidate voters, suggesting the election will only be valid if he wins. Above all, shattering every norm that gets in his way.
That last bit is what I really expect. Breaking unwritten norms has been a hallmark of the Trump presidency, and I’m sure someone has been holding him back. This is the only election he has left, so I’m sure he’s picked out a big batch of norms to start shredding on the morning of November 4th. He’s not going to concede, he’s going to declare victory. He’s going to suggest that “patriot poll workers” should do whatever they can to locate and shred mail-in ballots. There will be lawsuits to stop vote counts, pressure campaigns on Congressmen, etc.