Hmm... I'm curious if this also puts a delay on the defeat of Japan, as well?
It was my understanding that after Pearl Harbour, the Allies convinced the USA to redirect the population's outrage at the attack towards crushing Germany with a united assault before then focusing on Japan (since of the two, Germany was considered the bigger and more immediate threat)? If said 'ultimate offensive' fails, then that's a lot of manpower and time wasted.
I mean, it seems unlikely that losing D-Day will somehow lead to an armistice or the Axis somehow winning, but it certainly buys them a lot of time. While Germany is still going to be in a lot of trouble, I'm thinking that this'll probably keep the heat off of Japan's back long enough for them to gain a much stronger foothold in East Asia and the Pacific.
...
Or not, I'm not exactly an expert on wartime history.