The never ending "GPU upgrades are coming" lie. The delivery and illogic have changed but it's still just dangling some wilted carrots in front of a group of desperate starving people.
Funny how often it is delivered with a "probably coming soon."
Meanwhile, the reality in 2016. As in RIGHT NOW, TODAY REALITY. Is more than $2,000.00 for a pair of D700s that have been baking away in someone else's nMP for a couple years.
There is no other option, except buy a whole machine with them already installed. It's crap, and even the Applogists know it's crap.
And as far as the ultimate dangling of future wonderfulness, the "who knows, maybe the 7,1 will have compatible GPUs and your fairy godfather, Tim, will sell them to you for a fair price" this is just more lying.
As I pointed out long ago, the boot rom for 6,1 contains the roms for all 6 cards it ever was possible to use with it. (Left and right versions of the ones you know already)
So, even if somehow the switch to TB3 and NVME drives still left every single pin on the connectors the same, (basically impossible) the cards would not work in 6,1 unless Apple went OUT OF THEIR WAY to make them work. As in SWAM UPSTREAM and either issued a firmware update for 6,1 or included EEPROM chips on new GPUs with roms written to integrate with 6,1 and 7,1.
I would like to see one of the Appologists tell this lie in person. I can't imagine them holding a straight face telling what they KNOW is a complete and total lie.
Logic and reason tell you the truth here. 6,1 is withering on the vine with its 2011 GPUs as its only internal GPUs ever. People who insist otherwise are lying to you.