Well-connected Apple (AAPL -1.92%) guru Mark Gurman reports that the iDevice maker's next iPhone and iPad will be unveiled at an event scheduled for March 15. The devices, Gurman says, will be available just three days after the unveiling on March 18.

The new iPhone is said to be an upgraded 4-inch device. The device, according to Gurman, will feature Apple's A9 processor (a two-generation bump from the processor in the iPhone 5s) and the camera subsystem of the plain iPhone 6. It's unclear whether the wireless subsystem will be based on the one found in the iPhone 6/6 Plus or the one in the iPhone 6s/6s Plus at this time.

The new iPad is expected to be a 9.7-inch model, a slightly overdue replacement for the current-generation iPad Air 2. The device is likely to come with upgraded internals and is said to support the company's Smart Keyboard accessory (though Gurman doesn't seem sure whether the device will come with support for the Apple Pencil accessory).

What will the launches of these products mean for Apple investors? Let's take a closer look.

An end-of-quarter jolt to iPhone and iPad sales?
Apple issued revenue guidance that was quite disappointing to many in the investment community. Not only did the guidance suggest that iPhone sales would drop, but that they would likely drop by a non-trivial amount. iPad is also expected to drop, but that product category is fairly immaterial to the company's top and bottom lines compared to the iPhone.

Apple's second fiscal quarters in fiscal years 2014 and 2015 ended on calendar March 29 and March 28, respectively, so I'd expect that the company's second fiscal quarter this year will end around the same time. This means that the new iPhone should actually contribute to the company's second fiscal quarter results, with the first full quarter affected by the device launch being the following one.

The more interesting of the two in terms of potentially driving product category growth is actually the iPad Air 3. The 4-inch iPhone isn't a new flagship device; it's a product aimed at trying to serve either cost-conscious customers or those who simply want a new 4-inch device.

The 4-inch could drive incremental sales (and if Apple hasn't baked it into the current guidance, could drive modest upside), but it's not a game changer for the category.

The iPad, on the other hand, represents the next step in what is very much the "mainstream" iPad. The lack of a refresh of this device probably hurt iPad results last fall, but should help provide a nice boost in sales once it's available (read more on how here).

What's the real reason for these launches now though?
I suspect that Apple held off on launching these products in the fall so that it could have products to launch mid-cycle. Apple's yearly product launch cadence generally means a big spike in interest, with a gradual falling off until the next major device launches.

By putting out both a new iPad and a new iPhone mid-cycle, Apple is able to stay in the minds of both customers and investors for longer. And given how rough the current product cycle is shaping up to be, Apple needs to pull as many proverbial rabbits out of its hat as possible until it gets another shot with iPhone 7/7 Plus.