If this means the Axis win, & that is not necessarily the automatic outcome, it has long term economic consequnces for the US. Through 1914 the US benefited from the relative free trade with Europe, that was large part of the foundation of US growth. Post 1918 trade was subject to increasing restrictions but not to a catastrophic level, & nothing close to the restriction brought on by the war 1914-1918 or 1939-45. Through the 20th Century roughly 60% of US manufatored goods, agricultural products, and raw materials were exported, the bulk of that going to Europe 1900 through 1950.
So what is the bad thing? Both Japans leaders & the Facists in Europe were very insular economically, some had bought off on the idea of autarky or related concepts, thus imposing policies that restricted trade & cut US businessmen from markets they had profited from. The other half of this was the relative incompetence and corruption of the 'business' or economic leaders of the Axis nations. Many were politicians or thugs with little business experience. The peace time economies they attempted to run were significantly less productive. Less for everyone includung the US merchants still doing business in Axsi controled territory. There were still so with significant trade in Axis nations. ie: the Ford factories in Germany, DuPonts partnership with IG Farben (Analine Dye), Davis Oil a US registered company that was financed by the Reichs Bank.
A Axis dominated Asia & Europe is likely to contiue this same dysfunction set of economic policies. The long range implication is US exports do not recover to early 20th Century, or possiblly even Depression era levels. The only possible growth region is Latin America, & the US track record there had been mixed for political reasons. Further, the economies there were fairly small & for the next decade had low growth potiential. So, the short version is the US economy remains at late 1930s levels into the 1940s & has a long term growth rate far below that of the 1940s or 50s.
To Digress
Leaving Roosevelt aside its clear this was one of the motivations of the warhawks. By August 1939 a increaing number of business men saw that Japanese economic policy in Asia, specifically China, Manchuria, Korea, Formosa as unprofitable to them. What trade they still had went through Japanese middlemen. This group was becoming increasingly invovled in the China Lobby. There was a similar dynamic for those with or of former European connections. Even if whatever president does not lead the warhawks they will still be active. Somehow in the current narrative for WWII the nazi fanbois have lost sight of the reality of US politics the last US peace years, 1939-41. It was a bit more complicated that the simplistc 'Isolationist Citizenry vs the villan Roosevelt'.