Apple:

If you update to iOS 10 beta, you can remove some built-in apps from the Home screen on your iPhone, iPad, or iPod touch.

When you remove a built-in app from your Home screen, you also remove any related user data and configuration files. This can affect things like related system functions or information on your Apple Watch.

Removing these apps might also affect other system functions, for that reason, I’ll probably keep most of these apps on my devices. But this definitely feels like Apple’s laying the groundwork that will allow users to set default apps — browsers, email clients, etc.