Apple has to do something radical when it announces the next iPhone, all but the most diehard fans agree, and it may even delay the next operating system upgrade in order to perfect a new take on its famous user interface. There is risk in that, of course ‘ even users of a generally unloved UI like Windows still resist when confronted with a change, as Windows 8 proves. But there is higher risk in doing nothing and becoming old hat so that, like Nokia, people forget how dominant you used to be. The user experience is certainly part of the challenge, especially as Android, so iOS-like in many ways, is becoming slicker and more interesting. With vendors like Samsung…