Trump's strategy has long been clear:

1) Lie about voter fraud in mail-in ballots.
2) Push base to vote in person.
3) Slow down mail so fewer ballots received by Nov 3.
4) Falsely declare victory on Nov 3.
5) Challenge ballots counted after Nov 3 in SCOTUS.

I think it'll fail.

Trump undermined this strategy by telling on himself.

He announced his USPS sabotage and why he appointed Barrett.

Dems responded with HUGE early turnout, getting mail ballots in early and voting in-person.

Wide Dem margins and/or early Biden red state leads would thwart this.

On top of that, the media won't play ball. In 2000, Gore had to deal with the perception he lost because the media reversed the Florida projection. That hung over his recount efforts.

That won't happen. Media and social media is prepared for Trump's false declaration of victory.

If a challenge does get up to SCOTUS, Trump's argument is all predicated on pure lies. Would they really throw out ballots with zero evidence? Not likely.

For the same reason Barr hasn't charged Biden, I don't think SCOTUS would do this. Trump's public pressure taints them.

I know all that sounds optimistic, but I think the most likely outcome, is that Trump's efforts to steal the election will fail, and his whining will ultimately just serve as an excuse for his loss.

The real danger comes from how his base will react to his loss.