What would happen if the British decided to finish off Libya instead of moving into Greece, taking out Tripoli before Rommel can arrive in force? Let's say that somehow Churchill is convinced that Greece is a bad idea and doesn't opt to intervene, leaving the Greeks to handle the Italians on their own.
Does Germany not then invade Greece and leave that to the Italians? What do the Brits do with Libya? Could Tunisia/Vichy North Africa become a front or would the British leave that alone? What happens to Mussolini and his political career? If Germany does invade Greece does it fall much quick and Crete with it? What does that mean for the rest of 1941?