Apple could release a 5k monitor that uses MST over thunderbolt 3 to combine 2 displayport 1.2 streams. Both displayport 1.2 streams can be carried over a single thunderbolt 3 cable and there would be bandwidth left over for other peripherals connected to the monitor. Its probably not a coincidence that OS X got better MST support around a year ago and supports the Dell 5k display (which uses MST).
AMD is bringing displayport 1.3 to its graphics cards this year. One question is whether the displayport 1.2 limitation is due to skylake processors or if its the specification itself. Could Apple use displayport 1.3 with thunderbolt 3 if the source was an AMD graphics card? Maybe the display would only support new macs with discrete graphics initially until Intel built it into their integrated graphics.
AMD is bringing displayport 1.3 to its graphics cards this year. One question is whether the displayport 1.2 limitation is due to skylake processors or if its the specification itself. Could Apple use displayport 1.3 with thunderbolt 3 if the source was an AMD graphics card? Maybe the display would only support new macs with discrete graphics initially until Intel built it into their integrated graphics.