Actually this might be doable. From what I understand much of the former Soviet Central Asian republics (or at least their leaderships) were pretty pro Soviet vs. say the Baltic Republics or the Ukraine. In OTL for most of them the former local heads of the Communist party/establishment ended up staying in power to my knowledge. So it might be relatively easily possible have a break up of the Soviet Union with Kazakhstan joining up with post Soviet Russia or a Soviet Rump state including Kazakhstan.