Google and their maps
Its clear right now why Apple dropped the maps when they did. With the outrageous demands from Google of integration and propagation of their (now competing) services there was no way Apple would sign another contract next year. Keeping the old maps would mean falling yet another year behind and giving Google yet another year of support of their maps from the iOS users all while well knowing it would inevitably end.
Google maps got major improvements while being on iOS, the feedback and error reporting alone for 5 years was the best deal Google could ever get .. on top of that all the advertising from Apple .. and it isn't good enough for them.