The Soviet Union came apart because it overstretched itself and ran out of money and ideas. Local elites saw no benefit in remaining part of a bankrupt country. It fragmented along the administrative borders of the 15 republics that made up the giant country.
Yet there was no reason why the process had to stop there. Indeed, many of Russia’s regions—including Siberia, Ural, Karelia and Tatarstan—declared their “sovereignty” at the time. To prevent further disintegration Russia’s then president, Boris Yeltsin, came up with the idea of a federation, promising each region as much “sovereignty as it could swallow”.
Which is interesting.
It is also interesting that Russia's regions are having money problems:
Russia has entered its second recession in six years. The effects of the country's economic downturn have begun to trickle down from the federal level, spreading to Russia's regions, cities and people. The federal government has long relied on the regional and municipal governments to carry their own burdens, and many are teetering on the verge of bankruptcy or collapse as Moscow siphons off a growing share of their funds. The Russian people are also beginning to feel the economic pressure more acutely as an increasing number of citizens fall under the poverty line and watch their savings dry up. ...
All of Russia's regions must meet a series of burdensome obligations to the Kremlin and social spending. Of the income each region generates, only 37 percent stays in the region itself; the rest goes to the federal government. The Kremlin returns a small portion of that in the form of subsidies, though no more than 20 percent of the original payment. Since 2011, the federal government has raised regional taxes by 12 percent.
Could Russia break up again?
I've certainly wondered if Russia could break up again. I've thought especially of their Asian provinces as the new sick man of Europe staggers toward disaster in the west that the east doesn't want to ride along for.
Russia's empire broke apart after 1989 and 1991. I do worry that nuclear-armed Russia might not peacefully go through a third.
That would be interesting in a very bad way.