The default apps are getting murdered in the app store through neglect, and largely by non-Apple, cross platform (or easily portable) alternatives.
Once that happens, Apple have a platform that looks quite like Android but slightly worse as the sandboxing stops those apps behaving correctly.
So they either need to make the native apps better in a way that I do not think they are set up (or want) to actually do, and try to be all things to all people in a fragmenting marketplace, or they need to make third party apps better on iOS by defaulting and letting them have more background access and talk to each other.