External thunderbolt GPU's are one solution as others pointed out BUT the bandwidth for gaming is not enough....I mean unless you have the combined bandwidth of 2+ Thunderbolt 2 ports aggregated. For video rendering and a few other tasks bandwidth doesn't need to be THAT high....I'd kill just to be able to plug in dual GTX 780Ti's or even 680's into each of my Thunderbolt 1 ports for better rendering in After Effects, DaVinci Resolve, FCP X (if supported), etc. allot of these apps you can assign a GPU for specific things to take the stress off your main GPU. I really hope Apple keeps an option open for dGPU, even if its not the top end one I firmly believe dGPU's will for much of the future the best choice.