POD: Justinian does no more than offer some diplomatic gestures in the Vandal succession crisis and certainly, no matter what, does not invade! So, no Vandal Wars (which, of course, might mean that Justinian doesn't invade Italy either ... but that's a related, but seperate, question.) Finally, due to butterflies, a certain great Prophet is not born or, if he is, follows an entirely different path.
My question for you: How does the Vandal Kingdom evolve?
My personal guess, is that religion becomes less of a factor. Much as would happen to the Lombards in OTL a few centuries later, the Vandal leadership was involved in a factional dispute between those who stayed loyal to the Arian faith, and those who were Catholic. This is a big deal, of course, because there were not a lot of Vandals, and their religion was one of the biggest things keeping them as a distinct entity from the Catholic population.
So, lets say that the Catholics win out (which I think they eventually would, in the absense of a major turn around), and the Vandal ruling class eventually merges in with the rest of the population. North Africa, especially Tunis, is likely called Vandalia (or Vandaland ... but I prefer Vandalia). How does this Kingdom develop over the next several centuries.
Another aspect: Language. The Vandals spoke a East Germanic language, which was close enough to be called 'Gothic' by some early historians. Now, I doubt the Vandal language would really prosper in North Africa, largely due to numbers BUT: what language developes in the region? The normal response, is that North Africa ends up speaking a Latin dialect. However, there are some reports of Punic surviving in North Africa as late as this period, which makes me wonder just how ingrained Latin really was at this point.
So, in conclusion, do we get a Vandalia which has close cultural ties to Italy and Spain, and is considered 'European', or something else entirely? I'm interested to see how people go with this.