The two major things that made it happen so fast OTL:
-communist block giving support to liberation movements
-anticolonialist USA dominating western politics
could be butterflied away / reduced in strenght without 2 world wars.
I'll dispute that. The major factors leading to decolonization included the fact that the most profitable colonies (India, Indonesia, Algeria, etc.) were impractical to maintain by force. Further, there was the issue that the vast majority of colonies were far from profitable.
Aside from the Fascist experiments of the 1920s and '30s, modern European culture didn't have the stones to do what it'd take to hold places like India or Algeria. Once the valuable colonies started going, the balance sheets would show just how much of a waste places like Niger or Somalia really were. Countries would release colonies, which would only highlight the value of doing so to their neighbors.
That said, regimes have appeared now and then that'd accept the actions necessary to hold colonies indefinitely. Libya is a prime example, as others have mentioned. Not only did it have only small areas of arable land, but the Fascists had a very successful program of settlement and ethnic cleansing going by the beginnning of World War II. Give them another two decades and the coast will have a solid Italian majority. Of course, the interior would have a very angry Muslim majority, and it is most of the country, but ultimately they'd be more helpless than the Palestinians.