The problem here isn't whether or not Apple can use a discrete video card. Of course they can. They problem is that they don't want to - at least for their cheaper line of notebooks. They don't want to have to go back to the day of sticking a Radeon 9200 into the ibooks. Which is exactly why when they switched to Intel, Apple was perfectly happy just using the integrated Intel graphics in the Macbook line... at least until Nvidia came along and offered them something much faster with only having to switch the northbridge on the motherboard.
Now intel isn't allowing Nvidia or AMD to make alternative northbridge chipsets for their i7/i5/i3 line of CPU's. Thus, Apple will be forced to either
1.) Use the (very sucky) integrated Intel graphics, causing consumers to complain that they are getting a "downgrade"
2.) Use a discrete video card which has the potential to hurt battery life and have added costs which would hurt Apple's profit margins - something we all know Apple doesn't like to do.
Now intel isn't allowing Nvidia or AMD to make alternative northbridge chipsets for their i7/i5/i3 line of CPU's. Thus, Apple will be forced to either
1.) Use the (very sucky) integrated Intel graphics, causing consumers to complain that they are getting a "downgrade"
2.) Use a discrete video card which has the potential to hurt battery life and have added costs which would hurt Apple's profit margins - something we all know Apple doesn't like to do.