Even without the SU, America could outproduce Germany. So Hitler still had to battle GB and America. Remember, during WWI after Russia surrendered, Germany had an extra million troops to go to the western front. They still lost.
In the end America's huge capacity for resources plus manpower would do in Germany. Germany had the V2 rockets, but America was developing the atomic bomb. In the end, Germany would be worn down. Or Berlin destroyed by an atomic bomb.
You could also say if Heisenberg wanted Hitler to have the bomb he could have built it first.