Marshall had no explanation for the missing SDK other than to note that iOS development was once headed by Scott Forstall, but with his departure last October, the reins were handed to Craig Federighi, who already led OS X development.
Jony Ive, formerly head of industrial design, was also put in charge of what Apple calls "Human Interface," the user interface (UI) and user experience (UX) of its software.
Marshall speculated that the 2012 management overhaul, and Ive's new responsibilities, may have slowed down iOS development.
The same could be said for OS X 10.9, the successor to Mountain Lion, which has not been sighted in preview form either.
Timetables notwithstanding, Marshall and White expect Apple to be busy this year on the iPhone front: Both believe Apple will refresh not only its flagship iPhone, but also introduce a lower-priced model.
"My model implies a $150 [bill of materials] for a low-cost iPhone, which translates into a $300-plus price," said Marshall in an interview today.
But after a swing through China and other Asian countries, and conversations with component suppliers there, Topeka Capital's White raised his price estimate.
"We are now projecting a $350 to $400 price point for the 'iPhone mini,'" said White in a research note last week. "We believe this price point will provide relief for those investors concerned that Apple would be sacrificing too much margin or brand to serve the lower price band of the smartphone market."
And what of another oft-discussed move by Apple, a bigger iPhone?
"If we don't pick up any data from suppliers that Apple is placing orders for 5-in. screens by the end of April, or in a couple of weeks, either the iPhone 5S will have the same-sized screen as the iPhone 5, or Apple will instead ramp [production] to the back half of the year," said Marshall.
Minus a lower-cost iPhone -- and a boost in the screen size to 5-in. of the flagship model -- Marshall said Apple would be staring at trouble later in the year. Failing either, his current estimate of 55 million iPhones for the year's fourth quarter would be unattainable.
"If the iPhone 5S is a 4.5-in. phone, and there is no low-cost iPhone, Apple would be lucky to ship 40 million in the fourth quarter," Marshall said.
Marshall's current fourth-quarter estimate of 55 million predicts a 15% increase over sales during the same period in 2012. The lack of either a low-cost iPhone or a 5-in. model would translate into a 16% decline, year-over-year.