There are a number of articles on the net saying how to properly set WB for night shots. Specifically for cityscapes. For example, one of them says to use fixed Kelvin values like 2500 for nice blue and 10000 for awesome orange. I don't get it. It's usually impossible to set manual WB using a gray card or even a white object in a frame due to extremely mixed light and/or distance. Plus the sun is below the horizon so Kelvin values cannot be applied at all even in blue hour.

How do you deal with the situation?

Would you fix WB of this image (taken with Canon 5D in raw, WB set to auto)? How?