but what if the chads hang in florida again
Florida actually looks to have learned their lessons from being an electoral embarrassment in a few past cycles.
Couple of reasons why I think Florida will be able to call a winner on Election Night (and why they'll do it before nearly a dozen other states):
1. Nearly half of the registered electorate has voted as of today (49.21%).
2. While more than of those votes are mail-in ballots (4,066,974), Florida began processing and counting those votes 22 days before the election, the earliest such period in the country. By comparison, PA, MI and WI can't begin counting until Election Day itself.
3. They have a deadline of Election Day for mail-in votes to be received, so there's no potential waiting for additional votes as in several other swing states (NC, PA, MN, TX, OH, IA).
So the four hour wait is mostly because it's going to be extremely close. If, however, Florida goes to Trump and we're looking at Biden hovering around 250 EVs, things could get dicey. Georgia would be the next potential leg up, as they also have an Election Day deadline and have already processed millions of mail-in ballots as well as millions of in-person early votes. However, I think Georgia is going to be even closer than FL and may not get called until after midnight. Plus, it's only 16 EVs to Florida's 29. If Biden loses FL and wins GA, he's still short a handful of EVs, and they'd have to come from states which are giving 3 days or more for "late" mail-in ballots.
Now, it's possible Minnesota will be a big enough lead that they can call the state without waiting till November 10th, which in conjunction with Hawaii and Georgia would put him over the line. Or Michigan (which also has an Election Day deadline) will finally complete its count, and the trifecta of GA+MI+HI or MI+MN+HI would work.
Short version is: If Biden wins Florida, it's over on Election Night. If he doesn't, it's quite possible we don't have a winner until 3-4am, but Trump would also be heavily trailing so arguing for "whoever's ahead should win" won't work for them either, unless they try to halt state counts of mail-in ballots, which would be a huge Constitutional crisis as the governing of elections is specifically left up to the states.
The chances of not having a winner until days later is relatively low.