The way things are going in Russia you are more than likely to have some serious Russian on Muslim violence which can change that demographic quickly. The Muslims in Russia also inhabit the former provinces around Afghanistan. Put your money on the Russkies they are 3 times more violent than the Muslims are and four times more cruel.
But they are well below a self sustaining birth rate of 2.2. In time they will be overwhelmed by numbers.
A couple of factors come into it. One: the Soviets got their collective asses handed to them in Afghanistan and they were a lot stronger then.
Two: the Americans are not fighting them now.
Three: under Putin, they are regaining their barbaric edge.
Four: they handled the Chechens and Georgians with an iron fist in an iron glove.
Conclusion: any fight will be cruel and bloody, but I must agree that the Russians will eventually win out.