There's a good reason why the Mac Pro has six Thunderbolt 2 ports: current Thunderbolt tech isn't powerful enough to drive more than one 4K display per port. Future computers shouldn't face that limitation, though. VR-Zone has leaked a presentation which suggests that Intel's next Thunderbolt controller chip, Alpine Ridge, has enough bandwidth (40Gbps) to drive two 4K screens at the same time. That could prove a big help to video pros who want multiple ultra-sharp displays without filling up all their expansion space.
Alpine Ridge might not be a one-trick pony, either. The controller should charge systems that need up to 100W of power, and it should use just half the energy of its predecessor. However, there may be a big gotcha -- Intel is reportedly changing connectors to provide all that added bandwidth and electricity. Adapters would let you use older Thunderbolt gear, but that might not be comforting if you've already spent a fortune on peripherals.
The company hasn't confirmed any details of the new Thunderbolt spec, and there's no guarantee that what we see here will reach finished hardware. You'll have to be patient if the leak is accurate, though. The presentation mentions a tie-in with Skylake, the successor to Intel's upcoming Broadwell processor technology. That would put any launch in 2015, if not later.