Lets assume that Hitler for what ever reason decides to fight his own personal demons and decides not to invade the USSR, well for a start he could have committed more troops in North Africa, imagine the senario that an entire Army Group was transferred to North Africa and in conjunction to the Italians the British 8th Army was put up against say 40 to 50 divisions Axis divisions (within this 6 to 10 Panzer Divisions) and say an entire Luftflotte or two, Britain with all her resources could not possibly repulse this, Egypt would be Axis within weeks and that the Suez Canal would be in Axis hands, meaning that the entire Mediterannean is an Axis Lake, soon to fall would be Malta, Crete, Cyprus and of course in the end Gibraltar, this would also put the Vichy French firmly into the Axis fold.

I would expect that after achieving this the Axis would somehow make a major push into the Middle East and with an additional Army Group being landed in The Levant two major thrusts being launched into the Middle East. Axis gains the control of the Oil supplies of the Middle East, Britain is starved of vital oil supplies, Germany and Italy begin to establish Naval bases in the Indian Ocean eventually cutting all supply convoys from the east via the cape.

If the Soviets don't move into Iran then the Axis will, i could se the possibilities that the Axis could reach India by 1942. Once the British have been blockaded with the numorous Wolfpacks sinking any merchantman daring to enter the danger field, by 1942 i would suspect that Hitler would go for broke and launch total war on Britain, with an all out attack on Britain, also to end Hitler refuses to declare war on America after the Japanese attack on Pearl Harbour, the Western Axis has by this stage has a "Britain First" policy.

v.R