No version of Thunderbolt is currently compatible with Displayport 1.3 or Displayport 1.4.
TB3 and TB2 are limited to Displayport 1.2 - which means that 5k can only be done at 30hz, though 4k can be done at 60.
They might be able to use a TB3 proprietary extension to transfer the image, as the bandwidth for it does exist - especially if they are fine with using compression before the transfer (which has the downside of adding latency). It simply lacks the required protocol support.
I've been wondering if they might do something like this. Ok, current and pre-release Intel chipsets don't support Displayport 1.3/1.4? Well they could fabricate their own chip to support it. It would be a crazy expensive undertaking, but not completely impossible.
I won't hold my breath, though.
This would kind of, a little bit, be like what they did internally in the 5K iMac, but that effort didn't have to interoperate with anything else.