On the contrary, there's no reason to believe the exorbitant initial cost would change at all. If anything, this would make it worse.

The reason textbooks can cost as much as they do is that demand is very inelastic - students don't have any real alternatives to purchasing textbooks (in most cases.) As a result, there's little downward pressure on textbook prices.

Without any reason to lower prices, publishers would absolutely take this opportunity to maximize profits by raising secondhand prices and taking most or all of the difference. Students will be forced to buy them anyway, so why wouldn't they?