“We had not been defeated by these superior Japanese forces. Midway to us at the time meant that here is where we start from, here is where we really jump off in a hard, bitter war against the Japanese.” – Ray Spruance

And adds further:

THE DESTRUCTION OF THE KIDO BUTAI! The Japanese First Air Fleet. That assemblage of aircraft carriers and air crews that up unto Midway were absolutely unstoppable and ever-victorious. NOT ONLY THOSE JAPANESE SHIPS SUNK BUT THOSE HIGHLY EFFECTIVE AND VERY ABLE AIR CREWS IRREPLACEABLE!!

From the time of Pearl Harbor until Midway there was one Japan, very strong, in the aftermath of Midway there was a second much weaker Japan. That latter NEVER ABLE TO RECOVER FROM MIDWAY.

Allied military planners, American and British both now able to concentrate 90% of the war effort against Germany without further fear of Japanese advance.

WITH HINDSIGHT MIDWAY MORE IMPORTANT THAN REALIZED AND NOT WITH MERELY REGARD TO THE PACIFIC THEATER ALONE!

Yet more thanks to isegoria.net

The British had moved a sizable fleet to the Indian Ocean and when Nagumo moved his fleet into the Indian Ocean, bombing Port Darwin on the way, it put to sea intending to fight. At the last minute, it realized how strong the Japanese were and took a course intended to avoid combat. Nagumo’s reconnaissance was as usual poor and he failed to find them. For the rest of the war, the British fleet stayed west of India in order to avoid contact with the Japanese. The United States using its remaining carriers in the Pacific established a convoy system to Australia and New Zealand. Japanese efforts to interfere with this led to a battle between carriers, which was more or less a draw. The Japanese, however, made no further significant efforts to interfere with the convoys across the South Pacific. The Japanese then attacked Midway, reasoning that the Americans would have to fight for it. They turned out they were right about this, but the American fleet inflicted a severe defeat on the Japanese fleet at that battle. As usual, Nagumo’s reconnaissance failed. From then on the Japanese navy fought an essentially defensive war.