Since I have purchased my Macbook Pro 13" (late 2013), I have been hoping to get an Apple Thunderbolt display. Unfortunately, the one that is available is pretty much out of date. So while I am still hoping that Apple will come out with a new one, I thought I would put on my "dream display" hat and write down those thoughts.
Because Thunderbolt 2 is kinda like a cabled version of PCIe 2.0 in 4x mode. Not quite the bandwidth that most people associate with video cards, but enough to run a decent card, my thought was why can't someone put a video card inside of a Thunderbolt display. After all we have the MXM standard which allows the video cards in some laptops to be upgraded. This way when I am docked at the home or office, I have a secondary card that may have some additional OpenGL muscle over the card in the laptop, while still allowing me to have a power saving video card in the laptop itself. I typically use my laptop in clamshell mode when it is docked so I don't use the laptop display in that case. If MXM is not an option how about the option to use the video card from the new Mac Pro in here.
The resolution of the display should be 4Kish and at least a 16:10 aspect ratio. I think 16:9 is a little "short" for me.
As for ports on the back of the display
1x Thunderbolt 2 in that allows a single connection to the computer
1x Thunderbolt 2 (again for connecting additional devices)
1x DisplayPort 1.2 (so I can daisy chain a second display if needed)
1x Mic, built in mic in the display would be nice as well
1x Speakers, the monitor should have speakers as well
1x 1Gb Ethernet
1x WebCam with light when it is active
4x USB 3.0 ports on the back
1x USB 3.0 on front or side
And make it less than $1000, if possible...