Did you know that Thunderbolt 2.0 has been out for near 1 years now, do you see it regularly in laptops or any devices?
Just because the standard is released does not mean its cost effective to add.
GPUs chips have a 5 year development cycle. That means that the Maxwell 2 (probably just Maxwell) was conceived and started its life 5 years ago.
Graphics card PRODUCTS have a 6 month development cycles, so the GTX980 was conceived 6 months ago.
To put that in context. The DP 1.3 was announced 3 DAYS ago...
Get where I am going with this?