Trigger Warning: Handwavery
What if everything that could possible go wrong for the British does in mid-1942 and the result is that they get rolled and Rommel gets to Alexandria no later than October. The Nile and Suez fall to the Axis, but they cannot move beyond Suez. Let's say that Operational Pedestal fails and Malta ends up surrendering and the extra supplies plus whatever else you want to throw in happens, perhaps Gott doesn't die and bungles El Alamein so badly that Egypt is lost.
So we are in October, the Axis is in Egypt, but can move no further. What now? How do the Allies respond to this? Is there still a Torch landing? Does what naval forces exist in Cyprus try and break out west? Can the Middle East be supplied via Iraq? Is there an attempt to mount a liberation offensive via the Red Sea/Italian East Africa? How do they cope? Might we see Operation Round Up in 1943?