Apple is reportedly currently working on a subscription service for various hardware devices, starting with the iPhone, according to Bloomberg. The idea would be for users to “lease” a device for a given time, with the promise of an upgrade with each new generation. This could also concern other products, such as the iPad or even some Mac computers. Just as you subscribe to its online services, such as iCloud or Music, Apple could soon offer a comparable system for its hardware devices. If it does, the firm could literally turn the cell phone market upside down. For a monthly subscription fee,…