Will a netbook save Apple's Mac business?

Wall Street expects Apple to report poor March quarter Mac sales growth this Wednesday. But has the good ship Mac stalled?

Silicon Alley Insider's Dan Frommer notes yesterday that Wall Street expects Apple to report that it shipped 2.1-2.2 million Macs last quarter, a 4 to 9 percent year-over-year decline.

That's the first time in more than five years that Apple has reported a year-over-year decline in Mac shipments.

(The last time was 2003, when Apple reported a 5 percent year-over-year decline, just ahead of the Power Mac G5 launch.)

Should we be worried? Probably not, Frommer says, because Apple is somewhat recession-proof in the sense that it follows its own ups and downs, such as the steep drop in shipments ahead of Apple's transition to Intel chips in 2005-2006.

With consideration to how hard its competition has been hit by the economy, it's good to be (relatively) small, agile Apple. But with consideration to the "premium" notion of Apple products, the company has weathered the economy fairly well.

And the company has only since been firing on all cylinders versus Microsoft Windows. And accolades continue to pile up.

[Read more: Why Apple's new ad campaign is genius, and why Microsoft can't win as 'PC']

Still, if Apple's lack of a netbook competitor is hurting the company right now, it may only be a temporary bruise in exchange for broader success down the road. Everyone suspects such a device is coming (but not everyone know the price point). But will it deliver?

The company has been hurt before by not refreshing stale iMac and Mac mini lines. But what of an entirely new product segment? The company certainly has a lot to live up to: last year, Apple reported 2.3 million March quarter Mac shipments, according to Frommer. That's up 51 percent year-over-year, thanks to the new MacBook Air.

Can it deliver another Air-like hit?

Will a netbook save Apple's Mac business -- or is the Mac business not in need of saving?