Here's what the analysts and sites are predicting:
RBC's Amit Daryanani: "Our supply-chain checks indicate that... AAPL will launch the iPhone5s and a more affordable but lower-end iPhone at the same time, in either late CYQ2 or early Q3. The low-end iPhone will have the same 4" form factor as the iPhone5 but will have plastic casing and no retina display... The product may have lower GMs than iPhone5/5s but should be accretive to AAPL's corporate GMs of 38%. Hence, we estimate this could contribute $22B in revenues and $5.00+ in EPS in CY14E, which suggests the product could be worth $50+ to AAPL's stock price."
Cannacord's T. Michael Walkley: "Based on our handset market analysis and discussions with suppliers, we believe Apple could launch a refreshed iPhone 5S this summer or during Q3/C2013 versus our initial expectation for a launch in June. Further, with a host of impressive recently launched high-end Android smartphones expected to ramp in Q2/C2013, we believe Apple could lose smartphone market share during 1H/C2013 and have reduced our Q3/F2013 iPhone estimates... We also believe Apple will launch a more competitively priced mid-tier iPhone for pre-paid international markets and have adjusted our F2014 estimates and ASP assumptions."
Credit Suisse's Kulbinder Garcha: "Our checks in conjunction with our Asian team point to Apple not only refreshing the iPhone 5 mid-year but also a specifically targeted low-end iPhone. We believe in aggregate this a positive as it can sustain top and bottom line growth (giving upside to our FY13/14 EPS of $44.92/$54.03), deal with the competitive ecosystem and volume threat from Android/Samsung and continue to drive growth in Apple's installed base."
DigiTimes: "The sources pointed out that if the components are all shipped smoothly, manufacturers should be able to deliver the new iPhones to retail channels in 1-2 weeks for them to be ready to sell in the third quarter."
iMore: "iMore has learned that Apple is planning the release of the iPhone 5S for this summer, currently for August. Next generation iPads, presumably the iPad 5 and potentially the iPad mini 2, may also debut as soon as this April."
KGI Securities analyst Ming-Chi Kuo: "We expect Apple will introduce its new iPhones and iOS7 in June, and start shipping the new iPhones (5S and low-cost model) in the FDD version in July. Both dates are earlier than last year’s roadmap. We attribute this to: (1) an effort to avoid repeating the fatal mistake of last year of the delayed iPhone 5 launch, which gave competitors room to grab market share; and (2) the new iPhones this year are mainly designed on the basis of the current iPhone 5, which suggests development time could be reduced."
iLounge: "The iPhone 5S is still months away from mass production, but our source suspects that the star feature will be an upgraded rear camera—perhaps featuring Sony’s 13-Megapixel sensor, plus the aforementioned flash upgrade—along with a processor bump. Current prototypes are codenamed N51 and N53, with July mentioned as the target date."
Commercial Times: Apple will announce three new iPhone models in 2013, and two of them, the 4-inch iPhone 5S and 4.8-inch iPhone Math (both featuring 8-mega-pixel cameras), will hit markets before the end of June, China Times reported citing Taiwan-based Commercial Times.
It would appear that the consensus right now is a July launch for the iPhone 5S.