“Britain can be taken out of the game or just contained.”
Scramble your fighters west of London when Germany attacks; Save the transport/maybe the destroyer. Make sure to save your fighters. Move whatever forces you have left to Canada. Build your ships in Canada for a few turns. Move up to the SZ west of London and build more ships there. Use your fighters as a deterrent because they can scramble. Have a few US warships join this squadron at the same time they move to off the coast of London. A threatened Sealion complicates this, but the infantry that will be built to defend London can be used for amphibious assaults later on. Paired with the three/four fighters that were saved, its a pretty powerful landing force.
“Italy can move into Russia via the Middle East.”
If they ignore Egypt/clearing the med. If they spend the time and money going into Egypt, it’s going to be fairly late in the game by the time they get any sizable force through the Middle East and into Russia.
“The USA could be kept busy by Japan in the Pacific.”
With all of America’s money and two rounds of building before war, surely America can spare two/three transports a turn and a warship or two (since they already have a warship in the Atlantic).
“Germany can push for a G2 assault on Leningrad (especially if turteling)”
Fortify Leningrad from an attack from the sea. When Germany attacks by land just move all those units back to Moscow via Archangel. If Germany attacks G2 make sure they can’t hit you by sea. If they hit you over land on G2 all they have is their starting units and 5 newly built tanks. As long as you keep Leningrad fortified, Germany can’t hit you G2 with any real force.
“Japan can move into Russia to also eat away of those 1 IPC zones.”
They have 18 infantry to contend with. They can take a handful of territories in the far east, but doing so gives Russia a 12 IPC bonus. It will take 2 turns of income before it pays off. If Japan only takes a handful of Russian territories, it won’t make a difference until later in the game. Additionally, Japan needs land units to go into China. So any units that are used to take and hold Russian territory aren’t being used to fight the Chinese. If Japan tries to march through Russia, Russia can move one step back every turn. This will lose money for Russia, but Japan will have tied down a large number of forces allowing the Pacific Allies a chance to gain momentum.