So if the Volga and Asian ethnicities are acceptable, why does one need to kick the Caucasus out? If it's purely economic reasons that seems like a puerile reason to break up one's country and if it's for cultural reasons that seems extremely discriminatory and sketchy.
I don't see what the use of the other part of the idea is. My ancestors on the side that my family name derives from were partly Litvak Jews, partly Great Russians from the area of Lake Peipus, partly Great Russians from the area between the Volga and the Urals, and partly Tartars, so I'm reasonably familiar with the layout of Russia ethnically and culturally, and I just don't see how the '7 Russian Republics' would be divied up.
Is that even possible with the current population distribution? I was under the impression ethnic Russians have a majority basically everywhere except the Caucuses and some enclaves, I'm sure there's a map of this somewhere...