MIGHT be the dominant superpower, Democracy does not guarantee good economic policy, especially if you are starting out with a country with no democratic tradition, a population mostly composed of illiterate and impoverished peasants, a weak entrepreneurial class, and a considerable suspicion of capitalism. Look at much of Latin America. (although, admittedly, a Russia with an economy as developed as Mexico's would still be richer than today's Russia).
Even if Russia succeeds in modernizing, it's not necessarily going to be MORE of a superpower than the US, at least economically. Russia isn't going to have that much of a population advantage over the US, especially since as a _democratic_ country it is likely to shed large chunks of the old Russian empire, and as a _successfully modernizing_ country it will go through the demographic transition well before the end of the century. Add to that the fact that it is going to have trouble matching the US in GNP/capita (low, low starting point, well behind even Italy or Ireland in 1914, and _no_ large European country has managed to do so. Italy has only about 63%, France 76%, even Germany 80%. The only large country to manage that is Japan, and I really don't see Russia as another japan), I would bet good money on the US still having a bigger economy than even the most successful modernizing Russia in 2005.
OTOH, it might be a _more influencial_ power than the US, if a US never stirred out of isolationism by Nazis and the Cold War follows a policy of "free trade, otherwise ignore" re Eurasia...
best,
Bruce