I don't have any skin in the game but am curious what these sites who have already paid out would do if somehow Trump's lawyers worked some sort of legal magic to actually keep him in the white house. I wonder if they would then pay out the other side of the bet or would even have the reserves left to do so. Would they then confiscate all the BTC on their platform and disappear, or try to use future user fees to stay in business? It would be interesting to watch for sure and if I held a lot of funds on some gambling site that had already paid out based on the election results, I would keep a watchful eye on the situation and consider withdrawing anything I couldn't afford to lose.
I'm not aware of any smaller books that are actually acting as 'the book'. These days there are the giant established books, and then there are a few odds providers that run the back end of most crypto betting sites.
I would expect the established books to take the hit and pay Trump bets. If they didn't, it would do serious damage to their reputation. (Paddy power actually paid out Clinton bets a week or two before the 2016 election as a publicity stunt. In the end they probably still made out ahead after the MSM ran with it and gave them tons of exposure)
For the rest I would expect the odds providers to take the hit, and if they ran off then you'd see some smaller books that don't have the cash or rep to protect fold up.
I know Stake came out and said they were paying Biden bets out of pocket because their odds provider was planning on waiting till Jan and they didn't want all the money tied up for that long. They were open about being on the hook if Trump does find a way to win.