The mobile phone is widely touted as the ultimate iPod killer, mostly because of the convenience it offers. By now, most are well-versed in the arguments. Consumers always have their mobile devices on them, even if they never listen to a single song during the day. The iPod, on the other hand, is an accessory, and most could make it through the day without it. And once storage levels increase, prices decrease, and interfaces improve, the iPod will eventually become a redundant portable.

Those arguments sound great theoretically, though the weeds are a bit more complicated. In reality, both devices will probably coexist for longer than most expect. And the iPod itself is a moving target. Sure, the basic concept has been the same since the first generation iPod rollout, but Apple is already pushing discussions on mobile functionality. The early experiment with the ROKR was a forgettable throwaway, though future rollouts will be more functional and compelling. Already, action is brewing in mobile-manic Japan, where Apple is allegedly brokering an early partnership.

Meanwhile, the shelf life of the stand-alone player could be longer than many project. Currently, the entrenched iPod is performing quite solidly, and most recently surpassed 50 million units. And looking ahead, a mobile replacement process will slowly evolve over the short-, mid-, and long-term timeframes. In the short term, the stand-alone iPod will continue to dominate, while mobile-based services gain early traction. In the mid-term, the iPod will also thrive, though an increasingly large number of users will begin to rely on mobile-based offerings. At that point, the functionality of the iPod itself will begin to morph. And over the mid- and long-term periods, music on mobile devices will push into the mainstream, though it is unclear that Apple will be boxed out of this future marketplace.

Also adding to the complication is the profile of the user in question. Die-hard music junkies will continue favor a high-end, stand-alone iPod for its superior interface and seamless iTunes connectivity, even if mobile devices offer comparable storage levels. And because the iPod itself is extremely portable, these fans won’t mind carrying it around wherever they go – just as they do now, right next to their phones. That makes the more casual user the current low-hanging fruit for mobile manufacturers and carriers, mostly because lower storage and less sophisticated interfaces are less important for these listeners. And to court more serious fans, mobile devices and services will have to offer an interface that is at least on par with the iPod today – something that is much harder to achieve in a convergent handheld.

Technological replacement processes are rarely neat and clean, and a growing iPod infrastructure will help to extend the party for Apple. For example, a number of iPod-enabled automobile interiors – many of which are just hitting the showroom – will keep buyers in love with their devices. Sure, the phone is more convenient for on-the-go listening, but integrated steering wheel controls and in-dash displays are hard to resist.

The iPod is preferred as much for its fashion as its function, if not more, and that will also play a critical role in the evolution of mobile music services. In the United States, the iPod brand identity is powering an uncanny lead, and one that will be tough to dislodge. So how can the mobile industry avoid a situation in which the stand-alone iPod sits comfortably alongside mobile music services for a prolonged period of time? Putting fashion first, a killer mobile device will probably help to tip the scales, especially if the model commands RAZR-like attention. After all, the RAZR fetches a higher price tag because of its fashionable look and ego-enhancing relevance, not for its underlying technology. And if the iPod proves anything, it is that the cool-factor on technology is critical to wide-scale adoption. With that in mind, mobile music devices like the recently-released Fusic from LG represent a good start, though it may take a music-focused answer to the RAZR to really get things jump-started.

Paul Resnikoff, Editor, Digital Music News