be headed for a drop

请问这个短语be headed for a drop是什么意思？出自上海的高中科普英语阅读文选p58,passage20，endangered species.原句如下：
Are discs going to disappear?Some experts say that in just five years, one third of music sales may come from download, not discs. DVDs could be headed for a drop as well.
帮忙找一下确切解释，谢谢！

be headed for a drop With barely a minute left on the clock, Daniel Welbeck headed in for England什么意思 I headed for the door是什么意思?? what will be prepered for a party for you is it just a moment ,for us is can be a whole life! It’s necessary to be prepared for a job interview.... things could be a lot worse for me. what would be your criteria for a top student?Explain. I should be good for five bucks a piece.是什么意思 A long, vigorous swim may be good for your heart