By Katie Marsal

Published: 09:15 AM EST

With Apple chief executive Steve Jobs skipping out on this year's Macworld Expo, investment bank Piper Jaffray isn't holding high hopes for new product announcements outside a pair of refreshed Macs, but said in a report Tuesday that a redesigned iPhone should surface in the months that follow.

"Predicting product announcements for this year's Macworld has been difficult with new iPods and Macs released in the fall and the relatively new iPhone 3G," analyst Gene Munster told his clients. "With [Apple marketing chief] Phil Schiller delivering the keynote, we believe it suggests there will not be any revolutionary products at this year's event."

Still, the analyst believes a couple of existing products could see a refresh at the annual conference, namely the iMac and Mac mini. Meanwhile, his hopes for a new iPhone -- at one time seen as having an outside chance of appearing at the show -- have been dashed with word that Jobs would not be delivering his traditional keynote presentation.

"While we believe it is unlikely that a new iPhone will be released at Macworld, we continue to expect a new model by the end of the March quarter," Munster wrote. "Specifically, we believe Apple could introduce a lower-end model that is slightly thicker due to the inclusion of a slider keyboard for students (texting) and business use (email) between $99 and $149."

Another alternative for a new iPhone could see Apple alter the value proposition of the $199 model by using a different material than plastic for the casing, or giving it a slightly thinner form factor, he added.

Munster, who maintains a Buy rating and $235 price target on shares of Apple, said his 45 million iPhone unit sales estimate for 2009 is largely predicated on his belief that the company will expand its iPhone lineup to include a lower-end model early in the year.