Tweedledum and Tweedledee
Agreed to have a battle;
For Tweedledum said Tweedledee
Had spoiled his nice new rattle.
Just then flew down a monstrous crow,
As black as a tar-barrel;
Which frightened both the heroes so,
They quite forgot their quarrel.
Trump is the monstrous crow, as black as a tar-barrel. He will be good for the US. The system needs a bit of shaking up. The Republicans and the Democrats — Tweeledum and Tweeledee — have messed it up with their kabuki. Their staged battles, costumes, flying through the air tricks, etc., is highly entertaining. The details of the stage design are a perfect metaphor for the existing political setup.
A disruption will dislodge the status quo and perhaps push the moribund system to a different (and likely better) equilibrium. Granted that Trump is no visionary leader with wisdom oozing out of him. But he is the mild heart attack that jolts a person to take a serious look at his life and turn things around, if I may introduce another metaphor.