Both Matthais & Cal raise good points, even if Cal is more correct. But back tot he question. What would have to happen to make the IJA wake up and make the changes necessary to be an equal fighting force to the US Army?
That would have been remarkably difficult. Japan only had so much production capacity, so much available steel, and also had centuries of tradition to overcome.
Every tank or SP or prime mover/towed artillery combination took steel that could go into warships & the IJN had been, virtually from the moment Perry arrived, seen as the critical force to Japan's defense. Japan had used the British Empire as their guide, seeing almost exact parallels between that island kingdom and Japan. Battleship or a division of tanks? The BB was going to win out every time, not just because of the defensive/offensive potential of the warship, but because domestically produced battleships were proof of a nation's status as a major industrial power.
The even more serious problem is that the Japanese had, as did every other army prior to the 20th Century, generations of tradition related to battlefield behavior and the importance of bravery and discipline to success. In Japan this was magnified in the interwar years as the Cult of the Samurai, along with many other traditions from the 16th Century, were used by the government to help convince the population of the correctness of the government's path. As I noted earlier, the other industrial powers had the belief in the bayonet mashed out of them by the horrors of the trenches, although it took FOUR YEARS for the British & French to understand the change that had occured (the Germans figured it out in about two years).
Just these factors would make it hard to shift the IJA to a different doctrine, much less to create a combined arms force capable of meeting the other industrial powers on an equal basis. You would probably need a POD somewhere in the 1700's if not earlier, with Japan controlling a reasonable stretch of the Asian mainland (i.e. what Japan was trying to do by invading China in the mid-30's) to allow for a different Japan. At the minimum you would need to have Japan lose the Japanese/Russian war since victory over the Russians in this war convinced the IJA
AND theIJN of how they should fight future wars.
As far as facing the U.S. with any hope of winning, that was something that Imperial Japan, barring the appearance of a miracle weapon, would never be able to achieve. Japan simply lacked the logistics, production capacity and gross manpower necessary.
One of the classic stats that illustrate Japan's difficulties is their merchant marine. At the start of the war with the Allies, Japan had 6.4 million tons of shipping available for all purposes. After subtracting the shipping co-opted by the IJA & IJN, the civilian sector was left with 2.4 million tons of available shipping transport to support the economy; unfortunately the civilian secton needed 10 MILLION tons of shipping to maintain the economy. Japan
entered the war 3.6 million tons of merchant shipping short of civilian needs, much less military requirements; this shortfall had been made up before the conflct began by foreign bottoms, mostly British and American, which immediately became unavailable as soon as the bombs began to fall.
Japan, an Island nation utterly reliant on off-shore resources,
entered the war with a quarter of the shipping needed to support itself. That kind of math will kill you every time.