IOTL it seems that it's passage was the result of bi-partisan agreement on it. Wilkie effectively revealed the interventionist wing of the GOP and ran on that platform, refusing to attack FDR on any efforts he did to support Britain. Dewey on the other hand, who likely would have been the nominee without Wilkie as the alternative, would have run on isolationism and attacked FDR over the Destroyers for Bases deal and made it politically toxic for FDR to intervene in the war in Europe by aiding Britain with free equipment or giving them sweet heart deals. So IOTL when LL was announced that was in significant part due to Wilkie tamping down the isolationists in his party and denying them a national voice; Dewey on the other hand would have given air to their opinions and rallied that side of the argument. Even in victory FDR wouldn't have found political allies due to the whipping up of anti-interventionalist opinion during the general election. IOTL Wilkie made the political scene a dialogue about how much to intervene, not whether we should at all.
Instead the Isolationists, most vocally championed by Robert Taft, wanted to spend on the military to ensure US security; that seemed to be something everyone in the US agreed on. So the US not intervening with LL would probably mean major spending on the military and a peace time draft, which will yield economic benefits.
Germany stalemated in the East and left with a hostile Britain, even if one beset by finance issues, would not really be what I'd call triumphant; it would certainly control much of Europe and have hobbled the USSR, but it would be contained in Europe by an endless conflict in the East and a Britain hostile to it and perhaps aiding the USSR in small ways.
Japan will still have the major problem of China. Japan just cannot digest China and the endless conflict there will bleed them out over the long term even without LL or foreign intervention. China won't be able to kick them out, but the war will drain Japan and leave her fixated and unable to intervene much anywhere else. Britain probably won't be that financially strong and the Empire will be falling apart; India was ready to go in 1942:
https://en.wikipedia.org/wiki/Quit_India_Movement
The Empire would unravel, just more slowly than IOTL thanks to MUCH better British finances (though still short on foreign exchange due to effectively spending it all in 1940 IOTL) and no Japanese invasion of the Asian/Pacific holdings undermining British legitimacy there.
Largely the US would be a powerhouse economically, never having spend as nearly as much ITTL (though without the benefits like educating huge numbers of men via the GI Bill, but also military service). It would have free reign outside of Axis dominated areas in Asia and Europe and probably would still have some trade with the Axis powers due to their need for US raw materials among other things. Obviously it is not a good world in which the Axis powers are still around to massacre people en mass, but OTL Cold War isn't happening, nor is Europe and much of Asia wrecked by the war (outside of China and Russia that is). It is certainly an interesting world in the Chinese sense.