Is there any hope that CS6 will get a 4K update
Aside from critical fixes and maintaining operating system compatibility most likely no further work will be done on CS6. It's not impossible, since on Mac apparently there is Retina support, but there may still be technical hurdles that prevent this liek the UI libraries' rendering code not being fit. I wouldn't spend too much time thinking about it. If it's critical to you, CC is way to go, otherwise you will have to live with things as they are and counteract them on the system level by using smaller resolutions...
Not an employee, but if I was the official answer is that they are prohibited from providing detalis of future enhancements, but if there was it would only be in CC, as that is current version.
Thanks for the answers, which were as I expected. I will check how bad it actually is in use if I decide to get the monitor, and if Intuos's zoom feature is a workable solution. Otherwise it will be bye-bye Photoshop, I'm afraid.