Yeah well once the fact that they won't use their battleships to shell Midway my idea of them actually able to make the Americans surrender pretty much vanished. With what they had they had no chance, especially in the ATL where they have supplies for 3 years.
On the other hand though, in the air the Americans are at a disadvantage with all the AA around. The Japanese ships are safe from attack.
Question is, will the Japanese actually do it? Will they invade Midway and fail horribly? What will that change about the Japanese doctrine concerning invasion? What will their next campaign be? I mean in the sea they got the advantage for now with 3 American carriers lost.
Even if they win the actual battle of midway on the sea, they still have to retreat without taking it.
What about the Aleutian islands? Would the Japanese strengthen it? I mean they took Attu and Kiska and they could take Adak and try for Dutch Harbor again when naval reinforcements arrive to take out the American cruisers and whatever battleships they try to throw at them.
I wouldn't say they have no chance, but the odds are less than 1 in 1000. If fog hides the boats but leaves the landing sight uninhibited (somehow) then it's probably a 25%, either way the odds favor the Americans. So it's safe to say that the IJN should NOT even try to make a landing. Making the marines surrender without battleship shelling is a no-no and so is starving them out. A siege can't last long if your loitering time is one week.
The Japanese would have a slight edge in air away from AA batteries after TTL Midway, but AA favors either side. Around the Japanese ships, Japanese air numerical and technological superiority (at this time in the war anyways) and fleet AA would make striking them suicide. Around the airstrip and the main supply base, the Americans can defend themselves.
Now, do they try to invade the island? I can see several possibilities since the IJN intel is faulty and the think they have a 3 to 1 advantage in numbers. I'd say maybe a 25% chance Yamamoto is satisfied with his victory and is content to let his ships shell Midway a bit before moving on to his next target.
Ironically the worse outcome comes from a better realization of the big picture. He invades Midway, but I don't think they would fail horribly. A week's worth of bombardment should take care of the PT boats. The real problem comes from the coastal defense guns and the submarines. Also the rubber boats are basically "please shoot me." What probably happens is that the invasion starts to go off horribly and they call it off, losing maybe 1/8 of them and causing insignificant and possibly no casualties (because they didn't even LAND).
Now let's suppose the coastal defense fire messes or some
highly unlikely series of events happen that allow the Japanese to get close enough to land significant numbers of rubber boats on the island. If it was going to be catastrophic failure, it probably would be called off with only some stranded, so to get here something when right for the attackers. I've seen many weird things in military history and I'm not willing to completely write off the Japanese yet (I mostly write them off though). The Japanese land, and I'd say they maybe got a 25% chance of taking the island. They are outnumbered, but their cruiser and destroyer only gunfire support provides more firepower than the coastal batteries. Even if the Japanese aren't trained to provide spotting from the transports, any amphibious marine force should be able to spot once they have a beachhead. The accuracy should greatly improve with a spotter, probably triple the number of hits. One about 1/4 of the coastal batteries are out, a destroyer can stroll in nice and close at 2 km and it should be very accurate at this distance, taking out costal batteries and allowing the attacker to move in closer. Midway Island falls and the crew are prisoners of war.
Now what? Well as a mentioned, the last paragraph probably doesn't happen. In all of likelihood, the rubber boats don't get close, so the Japanese can't actually take Midway Island even after TTL Battle of Midway. Their best chance is a surprise attack, which is blown. They do get a consolation prize of cruisers and 3 American carriers sunk.
The next moves? If they didn't bother landing a force a midway, I can imagine them strengthening their hold in the Aleutrian Islands, and take Adak. Maybe they might shell Dutch harbor. If they tried to land at Midway and called off when things starting going horrible, I imagine they are down 1/8 of the landing force (everyone else runs away). Once again here they might try to take Adak, but they would be more conservative.
The problem for the Japanese is that they didn't inflict any significant casualties in TTL Midway. Sure, they got away scot free, but every airman loss and ship lost hurts them. in contrast, for the USN, flattops are replaceable,, they just take some time to replace. What hurts is to lose planes, sailors, marines and experienced fighter pilots in increasing order of seriousness. Losing a carrier hurts since the planes need to ditch. Since the pilots are safe at Midway, the overall picture doesn't change much. The Ranger, which was considered too slow for the Pacific Campaign, can be recalled from the Atlantic. The Essex will be built. In the case where Japanese suffer some losses in an abortive landing losing around 1/8 of their men without putting a boot on the island (which means the marine casualties are very light), I can even imagine the Gutucanal campaign staring just 3 months later that OTL!
Yamamoto might realize this and chose to land his marines. He knows the landing will be a difficult task. Little does he know, there are more defenders than he thinks and the job is harder than he thinks. As in probably less than 1 in a thousand it will work. But if they do take Midway, it's a huge setback for USA. The Japanese will go to the Aleutian Islands. Adek is defiantly going down. Dutch Harbor might be kept out of Japanese hands, but it's certainly going to be within bombing range. The Japanese might also take some islands in the Southwest pacific. They might start building supplies for their island garrisons, which defeats the island hopping strategy when the USN tries to fight back. If an island has 3 years of food and water and lots of ammo, you can't ignore it. I can imagine in this case development of new fighters would be scrapped in favor of replacing losses, so the Grumman F4F is going to stay the most advanced carrier fighter for another three years.