With RCV, how likely is it that we know the outcome of this race on election night?
Well, as a technical matter that's equivalent to the odds of one candidate getting over 50%. Which I think is quite high but others may disagree.
Maine does not do RCV calculations until well after the election (after all ballots, including military ballots, provisional ballots and other ballots that are often counted weeks after election day, are counted).
Of course, if the result is something like the 49.8%-46.7% cited above on election night, you can certainly call the race, but there is a technical possibility of RCV changing the result. Based on experience in 2018, though, a large portion of voters will not even indicate a second choice.
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