So the idea of expanding through thunderbolt is a great idea, but in reality is it worth it? There is already thunderbolt PCI expansion chassis around the web already but you can use the external thunderbolt chasis and buy a magma pci chasis for video cards. This will work as long as you're using supported cards but I'd only do this if you want nvidia pro cards and cuda or just down the line when the gpu needs an upgrade and so far this is the only way. http://www.sonnettech.com/product/echoexpressiii.html This appears it will be able to fit the new firepro w9000 in a dual configuration but it may be a bit tight, I personally would go for the w7000 as that's all I really need or may just go with a single 780(confirmed working) for cuda cores. In the end I'd have to buy 3 of these for my setup simply because I need the pci-e slots, my setup would include (possibly) 2 w9000s or 3 w7000s, 3x 512gb pci-e flash, and the last chassis would include my avid cards. Not cheap at all... but this shows thunderbolt to be a great little I/O and in the future by thunderbolt 3 or later in the thunderbolt 2 lineup we'll see pci-e 3.0 chassis and 5 years 4.0. The mac pro is just as accessible but they seem to be going sadly for external expansion... Now I believe the dual cards in the new pro's are on 3.0 and hopefully dual 7000s or if cheap enough the 9000 option. Than basically I'd just use these for extra pci storage.