So much depends on what sort of regime governs Italy in the postwar world. One scenario I can see is where Mussolini lives at least until the mid-1950s or 1960s if he's lucky and the fascist regime remains in power. By 1941, Italian East Africa had 140,000 Italians and Libya another 120,000. In Africa, only the Union of South Africa, Algeria, Tunisia and French Morocco had larger European populations.
As mentioned above, Libya's Italian population had grown rapidly during the late 1930s and the fascist regime had planned to settle half a million Italians in Libya by 1960. These were agricultural settlements, and though they were short-lived one of the interesting aspects was that the settlers came in the largest numbers, half hailed from the Veneto Region. Considered the politically right-wing region in Italy, in East Africa the largest number of settlers also came from Veneto. Its interesting that large numbers of Italians had migrated to French North Africa and Egypt during the late 19th and early 20th centuries and were almost entirely from Sicily, whereas in Libya they were only 9.49% of the sponsored settlers. I imagine that migrants from Sicily and Southern Italy would be tapped as potential settlers.
After the war a huge number of Italians emigrated, below are the numbers of emigrants from Italy postwar. It is important to note that the majority of those going to European destinations were largely temporary and the majority (71%) returned home during that period, whereas for the Americas and Oceania that number was 21%.
1946-1976
Switzerland 2,330,337
Germany 1,137,831
France 1,032,758
Argentina 500,116
USA 488,483
Canada 440,796
Benelux 381,692
Oceania (mostly Australia) 359,381
Venezuela 260,048
UK 166,402
Brazil 124,227
Other Europe 60,925
Other Americas (mostly Uruguay) 60,127
In East Africa, the majority of settlers were located in Eritrea (75,000), with 45,000 in Ethiopia, and 22,000 In Somalia. Though there were a few agricultural settlements outside of the capital Addis Abeba, the majority of Italians in Ethiopia (some 40,000) lived in the city. There was still guerrilla activity against the Italians and despite the large road building projects, I imagine that Ethiopia might eventually be abandoned. Tigray was annexed to Eritrea and the Ogaden to Somalia and the Italians might grant new states independence with those new boundaries, eventually sowing the seeds of a future conflict.
If Italy remains in Libya during the 1950s it will become closer to France in an attempt to stamp out Arab Nationalism. Without World War II, King Farouk might maintain a level of respect in Egypt and as a result, Nasser may never come to power. If he does, Italy would probably back Britain and France in the Suez conflict, hoping to quash the Nasser regime along with keeping the Suez Canal open, as it is vital to Italy's maintaining control over East Africa. In Algeria, Europeans were a mere 10% of the population in 1954, but if in Libya they are already 30%, that would lead to a much more difficult decolonisation process. Additionally, when Tunisia gained independence in 1956 there were some 90,000 Italian citizens in Tunisia, and probably another 70-80,000 French citizens of Italian ancestry in the territory. If Tunisia becomes independent and at least half are welcomed into Libya, they would further boost the European population.