Historian John Keegan had a 'What If' re Hitler proposing that after running the Brits out of Greece when dumbass Mussolini lost his invasion there the Germans could have invaded Turkey and then Iraq using Vichy Syria as a base, and from there threatened both the Canal Zone, Iran, India, and southern Russia and its oil fields, killing several birds with one stone, securing an oil supply, out-flanking the Brits in Egypt, cutting off the all weather Lend-Lease routes through Iran, and threatening Britain’s most valuable colony India, with 20 divisions. They could have counted on most of the Arabs support as well, at least 90% of them . This sounds like a viable plan that could have won, if the right winger running Germany had been Hitler's rival Wehrmacht General Schliecher.
He was the General that managed and oversaw the 'Black Armies' the Germans were building and training in Italy, Spain, and Russia, until Hitler shot him personally in 1933, or '32, I don't remember off hand at the moment.