This is a very controversial problem and I have to say that first time I read your message I felt it like a heretic idea.
At first we have to mention that all nations (including all African nations) have their right to self-determination, that means they have an independent and absolute right to choose a form of state and government they want to live in. All nations in the world have realized and accepted that the colonization was not a legal procedure as it was previously accepted. At the present state, the whole area of African continent is divided into territories of sovereign states. NO RECOLONIZATION OF AFRICA WOULD BE LAWFUL.
As you have described, the situation in certain states is really horrible... But at first, these states must realize this fact. If they realize it and ask other states for help (that was a long-lasting problem of Sudan and Darfour), other states can send there troops or other material help. If they do not accept the fact that they have a problem to maintain order at their territory, they will not ask for help and no state can come and help to resolve the situation because this will be a violation of their sovereignty.
This means that you can't help them to resolve their problem, not even gain their sovereign power without their consent - and that is a problem. These nations are so proud about their gained sovereignty and appreciate it so much that they will probably never accept losing it again (in a form of coloniztion)
I don't want to write is too long - this is a very complicated matter, but I consider the only possible outcome to be to create a union of African states where more developed nations would help troubled nations to resolve their problems. No European former-colonizer is entitled to intervene into these relations and it would be automatically treated as an attempt to recolonize.
PS: I am a European but I understand this viewpoint on Europeans