Since Siberia wasn't an SSR, Russia would have been within its rights to put down a secession. It was easily strong enough to do that for all of the problems it had in 1991. So there's a legal prerequisite of creating a Siberian SSR, preferably before 1991.
If that's done, would going it alone be attractive? Siberia has lots of natural resources and a small population, which cries out for an outside protector. Russia is still the most obvious choice for ethnic and geographic reasons unless things get really bad in European Russia. If that happens, it's not likely to be much better in independent Siberia where the other Soviet breakaways, China, whatever factions arise in Russia proper and the Russian mob all try to manipulate events to their advantage.