Is the powderkeg that is Ukraine about to ignite into a war between the U.S. and Russia?

A close friend of mine asked me today if I thought Ukraine was about to descend into war. She doesn't follow international politics as avidly as I do so I wanted to give her a short answer, yet soon realized that the situation is too complicated to be explained properly in less than 300 words. Here's the best I could do for the casual newser after considerable cheeseparing:

If war does come, it will be a proxy war at best. America can't get involved directly because Russia is a nuclear power. Countries with nuclear capacity don't go to war openly because both sides fear nuclear Armageddon. Instead, they will fund and arm intermediaries to fight the other side through intermediaries funded by the other side, e.g., Vietnam is a classic example (US v. Russia & China and fought via Vietnamese, Cambodians, and Laotians), 

It is unlikely that the Russians will allow Ukraine to break away and join the European Union because the pipelines that provide most of the natural gas traveling from Russia to Europe flows through it. Too much money to be lost there. Added to the confusion is that Ukraine is a country split in half almost right down the middle by politics. The Europe leaning side in the West, and the Pro-Russian side on the East. Think of this country if all the Dems lived west of the Mississippi and all of the Republicans lived in the East. 

The last reason is: Ukraine is broke. They need something like 16 billion dollars just to keep the lights on. Russia has offered that money if they come under their full control. In fact, that's what started the protests. The president (Yanukovich) promised the people that he was going to lead the nation towards joining Europe, but then Russia offered to pay them a lot of money and then he changed his mind at the last minute. Nobody wants to live under the Russians expect the people in the East. 

Short answer: Sorry Ukraine, the West will do a lot of public bellyaching but ultimately we cannot keep Putin from enslaving you. We just don't have the money and our country is war weary. Plus, the US needs Russia's help in the United Nations in contain Iran and keeping the radical Iranian regime from getting a nuclear bomb. The US is broke, we can't afford to give Ukraine the emergency funds they need. US is set to pull out of Afghanistan this year ending 13 years of war which has cost us an estimated 3 trillion dollars.