Katy Huberty is Morgan Stanley's (NYSE: MS) managing director of PC and enterprise systems research. She's also a leading authority on all things Apple (NASDAQ:AAPL), and something of a superstar among Cupertino watchers. She's unabashedly bullish on Apple shares, yet she saw the writing on the wall before Apple reported weak sales in July.

In short, Huberty tells it like it is when Cupertino is on the table.

I'm (re-)introducing you to Huberty's expertise, because she has a unique prediction on Apple right now. In "early 2013," she believes that Apple will finally ship iPhones to the last nationwide American network.

The leading smartphone was long exclusive to AT&T (NYSE:T), but Verizon (NYSE: VZ) and Sprint Nextel (NYSE:S) joined the party in 2011. The three largest carriers are now fighting tooth and nail over potential iPhone customers -- but T-Mobile USA is still on the outside looking in.

That wouldn't hurt so bad if Apple kept its network partners at least semi-exclusive, but that's hardly the case. In 2012, Apple continued to give T-Mobile the cold shoulder while much smaller operators got their hands on the iPhone. Apple currently lists support information for a whopping 16 American networks, including fringe players such as Bluegrass Cellular and Appalachian Wireless (also known as East Kentucky Network).

For crying out loud, local carriers Alaska Communications Systems (NASDAQ:ALSK) and General Communications (NASDAQ: GNCMA) battle over the 720,000 potential customers in Alaska, armed to the teeth with iPhones. But still, no love for T-Mobile and its 33 million users. If the proposed merger with prepaid specialist MetroPCS (NASDAQ:TMUS) passes regulatory hurdles, the two-headed carrier will sport 42 million accounts. Surely that's worth some of Apple's attention?

Huberty didn't dive into any detail on her prediction, except noting that the new distribution outlet might add as many as 2 million iPhone 5 buyers in next year's first calendar quarter.

This makes sense even without Huberty's proven ability to keep her finger on Apple's pulse. Technological hurdles to T-Mobile supporting iPhones are melting away, since the latest model runs on 4G LTE networks and T-Mobile is building one right now. Adding this network would have obvious strategic value for Apple, and T-Mobile has long been complaining about its iPhone-deprived status. There's just no reason to keep these star-crossed lovers apart any longer.

Fool contributor Anders Bylund has no positions in the stocks mentioned above. Check out Anders' bio and holdings, or follow him on Twitter and Google+. The Motley Fool owns shares of Apple. Motley Fool newsletter services recommend Apple and AT&T. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.