I want the audio book and ebook versions of the novel I'm reading to stay in sync with each other.
I want to listen to the audio book while driving around doing errands, then go into the store and read the ebook where I stopped listening to the audio book, then listen to the audio book in the car while I drive home, and then read the ebook while eating dinner at home. Amazon syncs Kindle ebooks, and Apple syncs iBooks - but the sync is only for reading the ebook on another device, not for listening to an audio book version of the same novel.
I want to be able to buy a Kindle book (or iBook) with a linked Audible audio book. Or buy a hardback and get Kindle and Audible versions which are linked. Oh, and it'd be nice if the Kindle ebook had page numbers which match the hardback book. Amazon owns Kindle and has a partnership with Audible, so they could do this.