Apple is doing phenomenally well these days. It seems it's doing a textbook job of maintaining huge market share in digital music players, long after most experts thought that share would erode. And it's doing so with the same proprietary strategy that many thought would never stand up to an onslaught from the likes of Microsoft (MSFT), Wal-Mart (WMT), and Yahoo! (YHOO). Can Apple keep it up?
I don't think so. Look at any industry -- not just computers and MP3 players. You also see it in aircrafts and software, and medical devices, and over and over. During the early stages of an industry, when the functionality and reliability of a product isn't yet adequate to meet customer's needs, a proprietary solution is almost always the right solution -- because it allows you to knit all the pieces together in an optimized way.

But once the technology matures and becomes good enough, industry standards emerge. That leads to the standardization of interfaces, which lets companies specialize on pieces of the overall system, and the product becomes modular. At that point, the competitive advantage of the early leader dissipates, and the ability to make money migrates to whoever controls the performance-defining subsystem.

In the modular PC world, that meant Microsoft and Intel (INTC), and the same thing will happen in the iPod world as well. Apple may think the proprietary iPod is their competitive advantage, but it's temporary. In the future, what will matter will be the software inside that lets users find exactly the kind of music they want to listen to, when and where they want to, with minimal effort.