My theory is that the Mac Pro hasn't seen an update because Apple knows that its current thermal design is a lemon, and they don't really want to sell any more of these because the replacement rate is so high.
Also, I think Apple will have to come out with a new display to go with the Mac Pro.
I must be missing something. If a new Mac Pro ever came out wouldn't it use USB-C and be fine on the new LG displays Apple sells (price dropped by the way)?
MacPro "SubZero Edition". :)