Trump answered "Maybe."
This has a bunch of people's attention. They see it as proof that Trump plans a coup to illegally retain power and ignore the results of the election.
If that were true, why would he telegraph his intentions?
It is like the Biblical story of the two sons asked to work in the vineyard. One said "No" but changed his mind and went to the vineyard. The other said "Yes" but the never got around to going.
I think it is more likely that Trump is putting the Democrats "on notice" that fraud will have consequences.
Consider one of the Obama elections. There were precincts where 100% of the voters were recorded as voting for Obama. Even if every voter was actually for Obama, what are the odds of all of them being able to correctly punch the correct chad or fill in the correct circle with the pen?
And there were no consequences for the perpetrators. There were no investigations. There were no independent audits to verify the highly improbable results.
Let's play this out with words.
Let's say the election goes slightly in Trump's favor on election day and then over the next several days votes trickle in via mail and tip it toward Biden. Suppose the numbers of votes and the ratio of B-vs-T votes followed suspicious patterns.
Trump files in court. The court will order investigation because there is almost two-and-a-half months from Election day until the Inauguration.
Trump publicly informed the Democratic machine that any shenanigans are likely to be exposed to the light of day because he isn't going to roll-over and let them clear the table without a contest.