Triple Retina 27 inch display?
What is triple Retina? I notice some posters interpreted this as three 27 inch displays. Others seemed to lean toward something more than a single regular Retina display.
(Since writing this post, I noticed the title of the original poster "Triple thunderbolt retina 27"," this would indicate Three Displays, but the first paragraph was written "triple retina 27" indicating a single very high resolution display.)
I would interpret triple Retina as either tripling the linear resolution (instead of doubling as in all current Retina products). This would mean, in the case of the current 27" display, going from 2.5K to 7.5K (7680x4320 pixel resolution). In this case 7.5K is actually called 8K (when not referring to 8192x4320 pixel display, true 8K). 7680x4320 is actually four times full HD (1920x1080)
Another way of interpreting "triple Retina", is doubling the linear resolution twice (4 times). So this would be 2560x1440 --> 5120x2880 --> 10240x5760 pixel display! This would be 59 MP (MegaPixels).
This 10K display would be more pixels than THREE 5K displays (Retina 27" at 14.7 MP). But FOUR 5K (27" Retina) is exactly the same number of pixels as a 10K display.
The current Mac Pro can support three 4K displays, which is 24.9 MP, therefore it can easily handle a single 5K (27" Retina) display.
We have GPUs today that can handle a single 27" Retina display, but the connector is the problem. ThunderBolt 2 isn't enough (at 60 Hz), and ThunderBolt 2 didn't even double the total bandwidth of ThunderBolt 1, it just aggregated the channels. Therefore a ThunderBolt "3" connecter would really be a change in the total bandwidth that may require different cables, possibly only optical fiber. Copper may not be compatible. Originally when ThunderBolt was being designed it was codenamed LightPeak and was intended only for optical fiber, but they found that less expensive copper would work. It's not a stretch to think that if they thought that copper may not work for ThunderBolt 1, it may not work for ThunderBolt "3".
I think "Double Retina", or "Retina 2" would be a better way to describe quadrupling the linear resolution of the original display, giving it 16 times the number of pixels. That's what 8K is to Full HD. 10K would be a "Retina 2" display of the original 27" Apple ThunderBolt Display (or 27" iMac). A "Retina 2" iPhone (2272x1280) with a 4.8 to 5.5 inch display is far more plausible than a "Retina 2" 27 inch display.
I can see stuffing 8K into 27 inches because that would give you exactly 326 ppi just like the Retina iPhone pixel density, though this is not needed, as we do not usually look as closely to a 27" display as we do to our iPhones. Therefore a "Retina 2" 27 inch display is out of the question, unless the number of pixels becomes trivial in 10-15 years. Then an entire wall with GigaPixels would be nice. For now this is just fantasy and beyond the scope of this thread.