The vast majority of Apple's (NASDAQ:AAPL) MacBooks use Intel (NASDAQ:INTC) integrated graphics. Only the highest-end, built-to-order configurations of Apple's 15-inch Retina MacBook Pro use standalone graphics, and even then, those GPUs are fairly low-end models.

The question I'd like to explore is whether, with Intel's next-generation Skylake processors, Apple will be able to completely cut discrete GPUs from its 15-inch Retina MacBook Pro lineup and use integrated graphics in all of its MacBooks.

Where are we today?
The latest 15-inch Retina MacBook Pro can be configured with a Radeon R9 M370X graphics chip. According to AnandTech, this is essentially a variant of the older R9 M270X graphics chip. A quick check of the database at GFXBench, a popular 3D graphics performance test, shows that in the Manhattan subtest, the R9 M270X averages 104.2 frames per second (higher is better). In the T-Rex subtest, the R9 M270X scores 224.8 frames per second.

Note that these are all "off-screen" results, so all results are at comparable resolutions.

The GFXBench database also has results for Intel's latest Iris Pro graphics processor. The Iris Pro achieves 66.6 frames per second and 155.8 frames per second in these subtests, respectively. That means the R9 M270X is between 44.3% and 56.5% faster than the current-generation Iris Pro GPU.

Skylake GT4e should be able to close that gap
I strongly believe that Apple will skip over the Broadwell Iris Pro chip for its next MacBook and go straight to Skylake. In going from the Haswell Iris Pro to the Broadwell Iris Pro, Intel increases the graphics "core" count from 40 to 48 (a 20% boost) and also enhances the underlying GPU architecture.

With Skylake, Intel plans to move to a new graphics architecture and will upgrade the GPU in the Skylake Iris Pro to include 72 next-generation GPU cores, up from 48 in Broadwell. According to a recent leaked Intel slide (by way of Guru3D), the Skylake Iris Pro should deliver "up to 50% better 3D gaming" relative to the Broadwell Iris Pro.

We don't know how much faster the Broadwell Iris Pro is expected to be relative to the Haswell part. However, Intel claims that in 3D graphics, the 24 "core" GT2 graphics in the 15 watt Broadwell-U parts is "up to 22% faster" than the 20 "core" GT2 graphics found in the 15-watt Haswell-U parts.

If we play it conservatively and assume a 15% performance increase in going from Haswell Iris Pro to Broadwell Iris Pro, then this would imply that Skylake Iris Pro is "up to" 72.5% faster than Haswell Iris Pro. If these GFXBench results are representative, then I could see the Skylake Iris Pro model as adequate to allow Apple to eliminate the discrete GPU 15-inch Retina MacBook Pro option.

What would be the benefit to Apple?
Apple of course could use the GT4e Skylake model to significantly improve the "baseline" 15-inch Retina MacBook Pro model and still offer a higher-end discrete GPU option for those willing to pay extra.

Another course of action that Apple could pursue, though, is to take advantage of the board area and power consumption savings that come with moving to integrated graphics and make a thinner, lighter system.

One flaw that I see with this potential strategy is that Apple would need to find other ways to drive upsell from the $1,999 model to the $2,499 model. It's not clear to me what Apple would do in this case, as there are seemingly a good number of folks who are willing to pay a substantial premium for the peace of mind that comes with a more powerful standalone graphics processor.

It probably won't be too long until we find out
Recent leaks suggest that Intel will launch its Skylake-H chips suitable for the 15-inch Retina MacBook Pro in the September timeframe. If true, then I don't think we'll need to wait too much longer to see whether Apple will keep offering standalone graphics options for its top-end 15-inch Retina MacBook Pro going forward.