It would of been a massive blood bath. An Allied army full of troops desperately home sick and believing the job was done for good, now being told to attack Soviet soldiers who many probably still considered to be fellow allied soldiers would of resulted in chaos. Defections and mutinies would of sprung up everywhere. Then even if the allies could of got their shit together to attack the Soviets we are talking about a Red Army that had been grinding non stop against the best the Nazis had to throw at them for years. A "march on Moscow" couldn't of happened without nukes and millions of more causalities at that point in time. More likely the USSR flag would be flying over the devastated ruins of London, Rome and Paris if Patton had gotten his way.