I wouldn't say it's ASB, especially considering the divergences and subsequent butterflies that have already occurred in the timeline. It would be very easy for America to experience a "red scare," especially after a successful communist revolution in Germany. If Red Germany or the USSR were to try to, say, incite a communist revolution in America that would most certainly turn America against them. And I wouldn't put it past the Comintern to try that.
There's also Mexico. Perhaps there will be a Comintern version of the Zimmerman Telegram? I believe its too late for any interference in the Mexican Revolution - but a more socialist/leftist Mexico after the revolution could easily make Americans fear communism as well.
People often over estimate anti communist sentiment. While there were pre 50s red scares, the reason why the 50s red scare was actually effective at reaching most levels of society was because they felt that communism would threaten their post war prosperity - america at this point, pre new deal, was very unequal and taking an anti communist stance is pretty dangerous, that's partially what caused Hoover to fail besides his ineptitude.
FDR won't get votes by going anti communist, and as I said, he wasn't merely ambivalent to Stalin or considered him an ally, he admired him. FDR's support base was also strictly anti Fascist, and allying with Mussolini would be seen as heretical and it would kill his chance for re election.
Japan remains the main threat in FDR's mind - and that may lead to the situation I brought up. Granted, assuming FDR loses this could change, but that's unlikely.
Also sorry, Communist Zimmerman telegram doesn't make much sense. The only way would probably be as mentioned above, a successful business plot or a Fascist America.
America will get economic revitalization, but this time probably focus exclusively upon Japan.