A similar effect http://www.plemasson.fr/shader.html seems possible in real time for game post processing. But tricky to get right as you can see.
The biggest problem I see with such effects is that they make the image artificially noisy and hard to see - it gets harder to understand the visuals and get a feel for how the 3D space is structured. It definitely looks pretty in a still image, but most games feature nearly constant movement and a visual designer needs to take into consideration the strain such filters put on one's eyes.
Isn't that the point of an impressionist filter; to just give you an impression of what was there before?