Russia has been keeping it's military aircraft industry alive since 1991 with export sales. Most of the sales have been to India and China. The profits have kept research and development going, but only at a minimal level. The Russians estimate that it will cost $20 billion to complete development of aircraft competitive with the F-22 and F-35. Even at that, the Russians see themselves as 10-15 years behind the United States.
China might be willing to come up with that needed money to develop competition for the F-22 and F-35, but the Chinese are also taking a hard look at air warfare and the role of high performance aircraft. To the Chinese, spending money on better aircraft radars and air-to-air missiles might be a more effective way to deal with the F-22 and F-35. Even if China and Russia spend the money and effort to develop comparable aircraft, this will have to include high performance missiles, radars, other sensors and all manner of electronics. Moreover, the Americans have achieved their domination of the air by developing a new air warfare system, which includes AWACS airborne control aircraft, lots of specialized software and intense (and expensive) training for the aircraft crews. There's more to air superiority than having the most modern aircraft.
Another major threat to Russian aircraft sales are the increasing number of used American warplanes coming on to the market. As the U.S. begins producing F-22s and F-35s in the next few years, more used F-16s, F-15s and F-18s will appear on the market. These aircraft are sold at bargain prices, and with proper maintenance, they have over a decade of service left in them. Moreover, American aircraft have a good reputation for effectiveness in combat, and good technical support from their manufacturers. The Russians don't score nearly as well in these two areas.
So, for the moment, unless the United States is willing to sell you F-22s and F-35s, and you can afford to buy them and keep the crews trained, you are a second or third rate air power. There's no other source of all the components needed to seriously threaten American domination of wartime air space. And it looks like the only other major manufacturer of modern warplanes will slide into oblivion.
Russia is in danger of being forced out of the jet fighter business. First, the end of the Cold War crippled Russia's military aviation industry. When the Soviet Union disappeared in 1991, so did orders for new Russian aircraft. Only in the last few years has the Russian air force begun buying aircraft again. The parts of the Soviet Union that split off to form new countries are still not buying or, if they are, they are looking at American aircraft as well. The Soviet Union had allies (called, more accurately, "satellites") in Eastern Europe that bought all of their warplanes from the Soviet Union. Those countries are now buying from American and European manufacturers. The lack of orders didn't stop development of new aircraft, but it slowed it down. Now, with the United States ready to mass produce it's next generation of warplanes (the F-22 and F-35), Russia is still mucking about with prototypes of their "fifth generation" aircraft.