During the alt-Russian Civil War in a CP Victory, have the Germans prop up the Idel-Ural State, the Cossacks of Don and Kuban, Kalmyk secessionists, Volga Germans, and north Caucasus secessionist efforts. Whatever regime pops up in Moscow will be cut off from the Caucasus and from Siberia with the Idel-Ural Republic standing in the way.
Rostov, Kuban, Kalmykia, North Caucasia, Tatarstan, Chuvashia, Volga German lands, and Siberia would all be lost to Russia ... at least until Germany gets distracted.