Earlier quoted context omitted.
The idea here is any video card you might want you can just plug in to a Thunderbolt 2 port. Six of those, which can be chained, is way better than having four internal slots.
Not quite. Note that Thunderbolt 2 can do 2x20G/bits/ per second, vs PCI-E v3 at 32G/bytes/ per second (on a 16x slot). Refs: - http://www.engadget.com/2010/11/19/pci-express-makes-the-3-0... - http://en.wikipedia.org/wiki/Pci_express - http://www.zdnet.com/intel-unveils-thunderbolt-2-7000016595/ - http://www.tomshardware.com/news/lucid-gpu-graphics-thunderb... - http://www.tomshardware.com/reviews/pci-express-graphi…
Hopefully Thunderbolt performance will continue to improve, though, and it can leverage all of the improvements to PCI-e.
The fiber version of Thunderbolt/Light-Peak could probably fix a lot of these issues with copper signal limitations. At this point the electronics in the Thunderbolt cable are so expensive that switching to a more expensive cable with no electronics might be a net win.