Bidding for address pairs ends in 2 hours.
What if all of the 200 address pairs aren't sold?
Would the highest bidder get all of the remaining ones? (even though it sounds crazy to me)

Yes. That is the way the bidding works.
It would be pretty unfair as only one person could own a hundred address pairs

It should be better to exclude the unsold ones from the new contract to prevent only one person from rudely harm the market by dumping a huge amount of TMEX once it is tradeable again ..