Predictitt does seem to work. I know a guy that bet on Trump winning and he made multiples of his wager. Hasn't taken the money out of his account, tho. Might parlay the bet into Trump staying in office through 2017.
As for the mortgage interest deduction, I believe someone in Team Trump said they wouldn't fully eliminate it. Looks like today's limit is at $1 million for the mortgage (~$40k interest deductible). Going forward, this might be up to a $300k mortgage, so only the well off are hurt. So, that would hurt home prices in the upper price range, but not in the 'normal' home market.