So basically, what if, instead of the Soviets taking power in 1917 and managing to keep Russia as a unified country Russia dissolved into a collection of smaller successor states following the end of WW1? What would those states be, how could they come about? One possibility, off the top of my head, is that
February never happens and Nicholas keeps Russia in the war until the country just breaks up. Another is that The Treaty of Brest-Litovsk is never signed and The Germans overrun the nascent Soviet government. In this case I imagine that we see a lot of Bolsheviks hung and the various nationalist movements at the periphery of The Empire declare independence while a German backed rump state rules over the old Muscovite heartland.