Touche...maybe not....they probably would have been too busy scooping up the numorous number of islands to solidify their empire. Afterall they needed alot of those places for oil, steel,etc....but let's remember...no US assistance means very long war....perhaps in time they would have been pressured by the other axis powers to assist. Afterall the German and Italian navy certainly weren't taking out the Brit's navy anytime soon. They would have needed that Japanese juggarnaut of a navy to help out. Perhaps they become more imperialistic and want more.
Japan did have eyes on India(England controlled at the time) and without US interference the outcome in the war against China would have been more favorable.( always a huge Japanese mistake in attacking China I thought-but then again they did seize a number of key resources there as well...sueing for peace was probably the best approach...China might have agreed to terms when they had their backs to the wall...to top that off there was Civil war going on in China at the time as well..The Ming(?), Han?, Ping?, Pong?, Ching?, Chang?, Walla walla Wing Bang?(whatever they were called) Dynasty might of welcomed peace to deal with the communist upstarts)
Also the Soviet Union extended back all the way to Japan. No fighting against the US means their forces would have to be placed somewhere. How about an invasion from the lightly guarded rear of Russia?..
or perhaps Japan takes the Panama Canal and moves into the Atlantic via that route? ...but then again the canal probably never gets built without a unified United States.