Also, if they do become Communist again, what do you think will happen?
There's no real evidence to suggest that it's even a possibility at this point. While Russia is ostensibly a democracy, at the moment the government is widely autocratic with Putin wielding power from behind the scenes. However, for Russia to begin an official transition back to a Communist system (by this I mean a fascist government calling itself a Communist state, like we saw in the past) the transition would have to serve Putin's needs and have a wide public backing. Currently neither of these conditions are true, Putin can govern effectively from behind the scenes and does not need such a transition to gain power and control (also, say what you will about Putin, but he is an intelligent man, he knows that such a system is not economically viable in the long run), and there is no sufficently large movement among the Russian people.
In the end however, while tensions have certainly increased greatly, there seems little reason to believe that a full on Cold War will begin once more unless the U.S. adopts policies and stances to delibrately provoke one.
What I personally notice when I hear the cries of "the impending war with Russia" is a feeling of nostalgia that seems to accompany the speaker when they discuss it. Among many of the advocates of taking a violent and militaristic stance towards Russia I suspect a certain amount of longing to return to the days of the Cold War, and the simple black and white morality of the day, as opposed to the more complicated conflicts of today. Dispite the blatant hypocricy of the U.S. suddenly demanding we respect other nation's sovereignty, the current dire condition of our military and economy after the policies of the past eight years, which leaves us in a poor position to enter a conflict with Russia, and the mutually assured destruction such a conflict would bring, I believe that many of the advocates of war would love a second Cold War to reinforce the black and white ideology they live by. After having to defend themselves for eight years on the disastrous war in Iraq, Guantanamo Bay and other secret prisons, and the torture that has gone on in them, warantless wiretapping and other blatant disregards of American rights, and the un-concealable corruption and incompetence of the current administration, I suppose many conservatives would enjoy returning to an age of black and white morality, where they would always be good and right, and their enemies always evil and wrong. In short, they would enjoy returning to a world where they would no longer have to think about complicated and grey issues, and where their ideologies would remain safe and unchallenged.