Sup Tobais... long time no see...
Back on topic...
The generally accepted outcome of the battle is that it was a stalemate, but unoffical Roamn victory and niether side had the forces to destroy the other but mainly Aetius not having the troops to complete the victory. Personally, studying the career of Aetius, we can see that even if he did have the forces to destroy Attila, (I think he did), he pursposely left him as a threat, because we have to understand that Aetius had a unique relationship with the Huns and Attila, (especially Attila's late uncle Rua), and so Aetius twice used the Huns to get him into his power positions, and if Attila and the Huns were gone, he knew that Galla Placidia and Valentinian III would have no need of Aetius any further, but his ability to "control" the Huns previous to Attila's campaigns ensured his position as the de facto ruler of the West, once Attila became hostile, Aetius, while needed, was slowly losing his power and influence since he could not hold the Huns over Rome's head like a threat that COULD be unleashed. They went from tools of Aetius to out of control ones and he ultimately suffered because he lost his control of them, so hence the reason he did not finish off Attila, because to do so would have completely destroyed his reason for being.
Let me add to that. Because of the invasions the Romans and Visigoths held a fragile alliance against this common foe. If the huns were destroyed, the alliance would no longer be needed, and the visigoths could continue their rants through Roman lands. One could only imagine why Aetius placed the Visigoths in the center of the line during the battle.