No. It took three major powers because to defeat the Nazi by 1945. Two of them would maybe fight longer, but the issue would never be in doubt. Nazis lose either way. Each of their enemy alone could match and surpass the war making capacity of the Nazi Germany. Hell, the Soviets outproduced them in weapons in 1942 already.
The Nazi policy managed to alienate the entire world, to corner themselves in such way that it was impossible for them to realize the full economic capacity of the areas they conquered.
I think the statement that "the issue was never in doubt" is by no means realistic. On the contrary, the issue was in doubt even as it was! Without any of the 3 big powers, it is exponentially more difficult for the germans to be defeated.
How will a Normandy landing be going with the germans having at least TWICE or more troops and weapons opposing them (if the USSR is out)? Would they even manage to obtain air superiority over France (let alone Germany) with thousands more Luftwaffe aircraft in the fray?
How would the USSR be holding the germans back, without the UK (and later US) forcing them to divert ever more troops and resources in the West and Africa?
How will the US even get involved in Europe, if UK is out?