Here's an idea: I've seen variations on the Pearl Harbor attack, on timing and damage, but what if there had never been an attack at all? It's the Day of Infamy that finally sparked the US into actively and effectively joining into WW2, but what if that hadn't happened?
Clarify: do you mean "What if Japan did not attack the United States?"
Because Japan also attacked the Philippines, Guam, and Wake Island.
I leave it up to speculation whether the Japanese would have gone after English or Russian outposts, that's a whole subject in itself.
Neither "England" nor "Russia" had any outposts anywhere. Great Britain and the Soviet Union had possessions in the Far East which Japan might have attacked.
The Isolationist movement was still very strong in the US, even for all our aid to England; without such an active act of aggression how long would we have remained "officially neutral". How long would Great Britain have held on without our full commitment? What reason, if any, would have been given should the US finally join the active war, assuming we would at all?
I guess the question you are trying to ask is: What if Japan had attacked British and Dutch colonies in SE Asia without attacking any U.S. possessions? That is really the only viable alternate strategy for Japan.
Japan was 'forced' (in their minds) to war because the U.S. (and Britain and the Netherlands) would not sell them oil unless Japan ceased its invasion of China. The British and Dutch colonies had the oil they wanted. (The Soviet Far East did not, BTW.)
They attacked the U.S. because they were sure that the U.S. would come to the aid of the British and Dutch, and the Philippines would be a huge hostile base right in their face: better to take it first.
Most observers think this assumption was mistaken; the U.S. would not declare war without being attacked, or at least very seriously threatened.
But the U.S. would continue supplying aid to the Allies, almost certainly on an increased scale. Quite possibly the U.S. would station forces in Australia, officially or unofficially, as a tripwire. The U.S. would reinforce the Philippines, and provide all possible non-combat support to the Allies. (For instance, by sending ships and planes into Japanese areas to locate their forces, and report the findings to the Allies.)
The U.S. would also continue its aggressive support of the Allies in the Atlantic, and there would be further clashes with the Axis.
This would, IMHO, lead to a U.S. declaration of war in 1942 - maybe as early as April, but perhaps as late as September.
Do not overestimate the strength of isolationism in the U.S. By 1941, public opinion had broken down about to this: 20% isolationist, 20% interventionist, 20% no opinion, and 40% support the Allies even if it leads to war.