"Does it make sense to, say, trade stocks on your Sansa Connect?" Mowrey asked. "We could do it, but where do you draw the line?"
As a result, users inevitably will have to choose between devices that do a few things well, such as a device focused on connecting to a music service, or devices that do many things, but not as well, Mowrey said.
"There are always trade-offs," Mowrey said. "For instance, phones typically don't have enough storage capacity to be great MP3 players, and [phone] batteries are challenging. If users use their phone to watch a video for five hours on a plane, when they get off the plane, the battery is dead."
The final challenge relates to how service providers price mobile access. Specifically, 3G access covers large areas, but the way cellular operators charge for it -- typically a flat rate of US$60 a month -- discourages its use in small, narrowly focused devices, Kerton said.
"Some devices don't use much bandwidth, and some are bandwidth-hungry like a video camera," Kerton said. "We need cellular carriers to start offering different rate and service packages. "Instead of AT&T charging $60 a month, they could flip it around and go to a company like [Global Positioning System vendor] Garmin, and that company could resell the minutes to their customers. As a consumer, let me pay a buck or two a month for some devices, and then I'll pay AT&T US$40 a month to connect my laptop."
Kerton said the cellular carriers have so far expressed little willingness to operate that way. But he was confident that such issues will be worked out over time.
"We're still in the early stages," Kerton said. "The Sansa Connect works well, and the iPod Touch works well, but we'll see a lot of devices that don't work so well. And we need carriers to offer different rates and service packages. But we'll hiccup through the process, and in five years, we'll be walking around in a cloud, and there will be bits and bytes available anytime you want."
David Haskin is a contributing editor specializing in mobile and wireless issues.