Your point is right on, we don't need to have results on election night.

One important point, though, is that a lot depends on the margin. Let's suppose Biden has even a small lead on election night - let's say a couple percentage points. And let's suppose he manages to get a court ruling that all mail ballots that are counted must have already been received by Nov. 3, those postmarked prior will not be counted. Even with this, once they start counting, in the swing states and Dem states at least, the vote is expected to be majority for Biden. If the whole pile of mail ballots is then counted randomly, it will only take a sample of a thousand or so to extrapolate with near certain margin of error how many of the pile will be for Biden and how many for tRump, and the results could be predicted the next day. tRump won't concede, but counting more ballots won't help him.

Even if tRump has a lead on election night - early voting indicates that he may not, but let's pretend - if the margin on the first sample of mail ballots is strongly in Biden's favor, we could still make accurate predictions from a small sample.

It may take weeks for tRump to concede, if ever. But the results of the election will be known long before he does.

By the way, you have a typo in the article - election day is Nov. 3.