Source: MacRumors.

It's official: Oct. 16 is the date to mark on the calendar as Apple's (AAPL -1.22%) next big product unveiling. As usual, the Mac maker has teased what it might have up its iSleeve with a promotional tag line, in this case it's: "It's been way too long." There are a handful of possibilities of what to expect from the event. What could the secretive company be up to?

The case for a new MacBook Air -- with Retina display?
Rumors that Apple was developing a new 12-inch MacBook Air with Retina display first surfaced a year ago, which was reportedly even thinner than the current models and featuring a high-resolution display.

NPD DisplaySearch, which specializes in display panel supply chain research, said at the time that Apple was looking into 2304 x 1440 panels for a possible 2014 launch. That would translate into 226 pixels per inch, which is in line with the pixel density of existing Retina models.

Current MacBook Air family. Source: Apple.

Other reports since then suggested that Apple might pursue a fanless design to enable the thinner form factor, as well as add additional color options, similar to the iPhone. The current MacBook Air design was introduced in October 2010 at Apple's "Back to the Mac" event, as one of Steve Jobs' final "One more thing" announcements. Four years fits within Apple's typical design cycle for laptops, so a redesign could be in order and line up with the tag line.

Why it's not ready yet
While the initial rumors indicated a 2014 launch date, Apple is counting on Intel's (INTC -2.40%) new Broadwell-Y Core-M chips to facilitate the fanless design. The first wave of these new chips was initially scheduled to launch in early 2014, but was delayed until late 2014 (in limited quantities) due to manufacturing challenges related to Intel's 14-nanometer process.

The chip giant said that "broader OEM availability" wouldn't be until early 2015. If the rumored 12-inch MacBook Air with Retina display is indeed to be fanless, Apple has to wait until Intel is ready to ship Core-M chips in volume, even if Apple is at the top of the OEM list.

Why Apple won't pre-announce
Apple did end up pre-announcing the Apple Watch months in advance, but there are some key differences that underscore why that won't be the case with a 12-inch MacBook Air with Retina display. Since smartwatches represent an entirely new product category for Apple, pre-announcing the device does not threaten sales of existing products. In fact, since competing smartwatches are already on the market, pre-announcing threatens competitors.

In contrast, Apple's existing MacBook Air and Retina MacBook Pro lineups could see purchase delays during the important holiday shopping season if Apple were to pre-announce a new product with overlapping selling features. Potential buyers of either existing product line might hold off if they knew the best of both worlds was coming just around the corner.

Don't expect Apple to unveil the rumored laptop until it's ready for prime time.