Would America remain neutral though? Granted, with the Fall of France there's probably going to be less enthusiasm for the Entente's cause, but is there any reason to suspect the Germans wouldn't resort to unrestricted submarine warfare here? After all, the war is largely a naval one, and Germany is under a blockade.
Though with continental Europe largely in German hands the blockade is obviously a lot weaker.
Also, how long would the US tolerate it? OTL, it was worth their while to do so, because exports to the Entente more than made up for the loss of trade with the CPs. But with no continental war going on, that is no longer true. To tolerate the blockade is to give up America's trade with almost everybody except Britain - and I don't see America putting up with that indefinitely.