The Sietch

Well, that isn't exactly in my wheel house, but I sincerely doubt that even voter fraud will work. The problem with voter fraud is that you need to know how much of a bump to give yourself. Go too low and you still lose. Go too high and you make it obvious you're cheating. Especially because those names and addresses have to come from somewhere. And if people get suspicious, it's pretty easy to get caught.

Safer ways of cheating involve methods such as late voting. That's what Arizona did in 2018. Their governor declared an emergency, kept the ballot open in blue areas for a full week and eventually took the senate seat away from the former winner. That's easier to pull off in the mid-terms than it is with the general, when the entire country is watching. SCOTUS I think just shot that idea down in Wisconsin, which tried to allow for late mail-in-ballots.

Finally there's ballot harvesting, which can shore up numbers, but again, you can't really conjure votes from thin air. It also either gets expensive or tends to have low turnout and thus isn't useful save for more local elections, where those sort of numbers can actually move things.
Overall, I don't think they'll win. Of the five states that I think are actually competitive, they would have to successfully make it work in all five states and then have enough votes to beat Trump. That's a hard balancing act.

Really what this all comes down to is party energy. Even though the Media is playing up Biden's popularity, the fact is that he has less in-party support than I think Clinton did. Of the people who would vote for him, only about 36% are doing it because they like Biden. Most of the rest are doing it because they're anti-Trump. When Clinton ran, she had I think like 48% who were excited about her and 50% who did it because they disliked Trump. So that isn't a good sign. Meanwhile, Trump appears to be more popular with his own party than he was in 2016.

But unless a state is within 1% of the vote, voting fraud tends to fail.

You think any of the swing states will go for POTUS by such a margin?

Possible. All signs point to a demoralized base.