This post about an independent Sinai has some stuff relevent to this discussion. Suez in the 1920s was 15% European, a mix of British, French, Greeks, and others and once Sinai is separated, that number will increase over the decades. I think the British would need to encourage settlement in Suez (and Sinai), and perhaps pull out of Sinai after some time.
One thing which would be helpful is an independent Egypt, either actually independent or "independent" and subject to the Ottomans in the same way Egypt was in most of the 19th century. Britain would still get Suez here and garrison it just as much, if not more. Probably a decent Royal Navy base since they won't have Alexandria. With an independent Egypt and the Ottoman Empire next door, the British would likely invest more in Sinai's development for defense should their diplomatic and economic efforts in the Ottoman Empire fail.
Another scenario would be a German victory in WWI around late 1917 or 1918 (no American entry TTL). Maybe have a better A-H performance or CP Sweden/Romania to help Russia collapse faster and take the pressure off Germany. The exhausted British Empire ends up negotiating a retreat from their Egyptian protectorate after German and Ottoman-backed revolts there but keeps Sinai (because no way are the British parting with that). Fearing hostile powers on both sides of Sinai, the British increase development efforts in Sinai, and encouraging businesses to open there and investing heavily in veterans from the war to do so. Sinai ends up with a mixed population of British, French, Greeks, Indians, Jews (from all over Europe thanks to encouragement of Zionism) as well as native Arabs.
