Significance: The chances for a credible alternative to iTunes increased when Apple seemed to be stumbling in the cloud, but it seems likely that it will remedy that with a major iCloud upgrade, expected at next month’s WWDC developer event. However, Apple can no longer take its leadership for granted as its major mobile competitors up their game. Some are still making hesitating progress – Microsoft and Nokia are moving too slowly in creating a harmonized hub, and Google Play does not come close to an Apple-class experience. But Amazon is constantly stretching its model to tie users in more effectively, most recently with its first full MVNO plan, while Samsung has relaunched Music Hub as the precursor for its…