Updated models with AMD graphics options expected in early 2017.
MacBook Pro's NVIDIA Chipsets Can Support Dual GPU and 8GB RAM
First of all, the new MacBook Pros are capable of switching from discrete to integrated GPUs "on-the-fly" without logging out. This should not come as much of a surprise, as there exists support for this real-time switching in Windows. So if and when Apple updates the drivers for the MacBook Pro, on-the-fly could be enabled. The benefit to this, of course, is when you move from word processing to playing a game, the GPU could switch from one to the other automatically without requiring a log-out.
More interesting, however, is the that the NVIDIA chipsets are capable of running both integrated and discrete GPUs simultaneously which would offer a large performance boost. There had been some debate about this capability before. Some of the confusion lies in NVIDIA's naming convention.
NVIDIA advertises two features under the marketing name "Hybrid SLI". The two features are:
Hybrid Power - which allows your to switch from one GPU to the other for better performance vs battery life. Apple's MacBook Pros do support this feature but presently require you to log out.
GeForce Boost - this is the feature that allows both GPUs to run simultaneously to provide even better performance (and presumably, even less battery life).
According to this most recent statement by NVIDIA representatives, the MacBook Pro's hardware is capable of both, but will need specific software support to be written by Apple.
Finally, NVIDIA confirms another interesting tidbit that had been circulating already. These new chipsets officially support 8GB of RAM. Prior to this, it appears MacBook Pros were limited to 4GB of RAM. This would be a welcome change for those who use their MacBook Pros for memory intensive tasks. This being said, we haven't yet heard of anyone who has successfully installed 8GB of RAM in their new MacBook Pro.