The two front war was an inevitability. The USSR was preparing to attack the Nazis, with a planned date of 1944-5. I suppose if more resources had been put into North Africa, the Brits could have been knocked out of the war sooner, but given the fact that the Nazis threw 80-90% of their military at the Soviets, I doubt they would have been able to succeed even if the USSR had their undivided attention.