Many of them were killed, many of them were sold into slavery, and many of them undoubtedly lived out there lives scarred by the horror that they witnessed. The city of Carthage itself remained devoid of urban settlement, despite the fact that it is a really good spot for a city, until it was designated as a location for a Roman colony by Julius Caesar. No doubt this colonization itself (and the earlier colonizations of North Africa) caused great hardship to the local people. I'm saying this because I really don't want to sugarcoat the process of empire for Rome, which is quite easy to do given what the next paragraph will be. The description of the sack of Carthage in Appian's Punica, particularly section 26, is quite horrifying--one particular detail that sticks out is that one street was so slippery with blood that the Romans could not pursue fleeing enemies down it. That being said.

Rome never, or at least never unambiguously, pursued a their policy of conquest on the level of population (what one might call "genocide"). There was obviously mass slaughter, but it was always towards a particular end, and not the end itself. So there was never a real attempt to "de-Punify" North Africa, as once the area itself was conquered, there wasn't really a point. And so despite the wars the area itself remained overwhelmingly "native" in origin, which means that the participants in the enormous prosperity of the province in later times would also have been overwhelmingly native. During the imperial period, North Africa became one of the great lynchpins of the empire and its economy, Carthage became one of the largest cities (perhaps equal to Antioch and Alexandria) and some of the most spectacular remainders of the Roman period are found there. Carthage was also one of the great cultural centers of the empire, and in Late Antiquity was in many ways the heart of the Latin Christian world.

The wealth of the province has been known about for some time, but the original assumption, bolstered by apocalyptic visions such as Appian's, was that it was a thoroughly Roman sort of place, with the old culture stamped out or at least relegated to the rural and poor. More recently this image has been turned inside out, and many of the indications that were used to show thorough Romanization have been convincingly demonstrated to show the opposite. For example, the Capitolium is a particular temple form modeled off of the Capitoline temple in Rome and basically only appears in Italy and North Africa. It was long thought to be a sign of imperial imposition, but recent scholarship by archaeologists such as Andrew Wilson and Naomi Norman have argued pretty convincingly that, for one, in Africa they were built on local initiative, and for two, they are best interpreted within an African cultural context. After all, the Carthaginians had their own triad of Tanit, Bel and Eshmun, and there are tons of Tanit related imagery throughout the period.

So the broad answer to your question is that despite the brutality of conquest, the Carthaginian people were the determinant influence on Roman North Africa, which became one of the most prosperous areas of the empire.

My big influence here is David Mattingly, particularly his Imperialism, Power, and Identity: Experiencing the Roman Empire. He is mostly interested in the enduring divisions and conflict in post-conquest provincial society, which I am mostly eliding over.