Most importantly, the states run the elections.

So he can "cancel" the election, but only red states would listen. Blue states would still hold elections and report results. And with red states not holding elections, it's safe to say any election would lean heavily left.

So republicans would only lose seats, and trump would get zero electoral college votes. Well, most likely every red state would still try to send electors for trump

After midterms we'll be able to see what's gonna happen if that plays out.

But honestly, blue states should be prioritizing building up their own NG the next three years just in case.