Source: Apple

Earlier this year, Apple (AAPL 0.51%) refreshed its MacBook Air and MacBook Pro family of products while at the same time introducing its new thin, light, and fanless MacBook design. Apple upgraded both the 11-inch and the 13-inch MacBook Air models, as well as its 13-inch MacBook Pro, to include Intel's (INTC 0.61%) latest Broadwell-U family of processors.

The 15-inch MacBook Pro saw an update shortly thereafter, but the system still used the same Haswell-based processor that Apple used in the 2014 model. 

Given that Intel has signaled its plans to launch chips based on its next generation Skylake architecture relatively soon, it seemed that updated MacBook Airs, as well as an updated 13-inch MacBook Pro using these chips, might be in the cards for later this year. 

But thanks to a leak of an Intel processor release schedule (via Fanless Tech), it looks as though the MacBook Airs, as well as the 13-inch MacBook Pro, might not see updates to the Skylake architecture until early 2016.

These aren't the Skylake chips you're looking for
Let's start with the MacBook Air. Investors familiar with Intel's low-power processor lines know that the company generally puts out two variants of these chips. The higher-end models will feature two hyper-threaded CPU cores along with what the company calls its "GT3" graphics configuration.

In the case of Skylake, it has been said that the higher end of these low-power chips will actually feature GT3e graphics -- that is, GT3 graphics with a fast, on-package cache memory to help boost performance.

The lower-end chips come with what is known as a GT2 graphics configuration, which should have approximately half of the graphics execution units as the GT3/GT3e chips. And, of course, the fast on-package cache memory isn't present.

In the MacBook Air, Apple tends to use the highest graphics configuration available from Intel. The processor list in the slides from FanlessTech appear to be parts with the lower-end GT2 configurations (as evidenced by the processor model number names) rather than higher-end GT3/GT3e configurations.

Although this slide might not contain all of the low-power Skylake chips that Intel plans to launch this fall, it wouldn't come as a surprise to see the higher-end chips launch early next year.

The 13-inch MacBook Pro definitely won't see Skylake until early 2016
FanlessTech also posted another slide showing Intel's product release plans for its higher-powered 28-watt "U" series chips, which Apple uses in its 13-inch MacBook Pro computers.

Source: FanlessTech

The slide clearly shows that Intel expects to launch the Skylake variants of these chips in the first quarter of 2016, which should allow Apple to refresh the 13-inch MacBook Pro at that time.

It's worth noting that the 28-watt low-power parts typically share the same silicon die with the higher-end 15-watt parts. This further supports the notion that the MacBook Air-worthy 15-watt parts won't be available until the first quarter of 2016.

How about the 15-inch MacBook Pro and the slim MacBook?
Although there's a good chance that Apple's MacBook Air and 13-inch Pro devices won't see processor upgrades until early 2016, there's still hope for both the thin-and-light MacBook as well as the 15-inch Retina MacBook Pro.

Intel's Core M processors are based on the same silicon die as the 15-watt GT2 parts, with the primary difference being that the Core M parts offer slimmer silicon packages. If Intel is launching 15-watt Core i-series parts with GT2 graphics this fall, then a Skylake-based Core M processor should be available at roughly the same time.

Indeed, Intel CEO Brian Krzanich outright said on the company's April earnings call that a Skylake-based Core M is set to launch in the second half of 2015, which makes perfect sense.

With respect to the 15-inch Retina MacBook Pro, there seems to be a reasonable chance that Skylake processors suitable for the device will be available later this year.

Intel recently indicated that its "Mobile Xeon" processors (based on the Skylake-H processor) will arrive in systems in the fall. Given that leaks show these parts to pack GT4e graphics, an updated 15-inch Retina MacBook Pro could still be a reality later this year.