you better be prepared to wait for that as DP 1.4 won't even cover that.
DP 1.3 should be enough for 100-120ish Hz 4K, with DP 1.4 being enough for 4K 96Hz with HDR according to AMD.
Thankfully DP1.4 should be faster to implement than 1.3, as it uses an almost lossless compression method to almost double the bandwidth.
DP1.4 will be added to things through software, which is why Polaris and Pascal GPUs are said to already support it.
The main problem with HDR is that it needs some super high-end displays to support it properly. Any low-end TV that supports it will likely only support it partially (only the deeper blacks but no enhanced colour, or doesn't have a good enough backlight).