Of course a strong Empire of the North in the 6th Century wouldn't be a centralized state. But what the WI is about is whether the kind of tribal federation Attila created, where the Huns dominate and the other tribes recognize and accept that, could continue.
No.
1)It was at the rupture point where the "ethnic" Huns represented maybe 25% of the raiding bands. Ostrogoths, Alans, Franks, etc had their own leaders.
Once the bully-in-chief died, they felt not really tied by any loyalty.
2)The rule of Attilla came from the fact he assured to the Huns (in political meaning) regular loot and redistributed enough. The issue was he probably reached the maximum he could : already he was defeated in Gaul, and somewhat in Italy.
When the other people constituents of the Empire saw that the germanic people that settled provincial regions of Rome had a clearly more stable and more enjoyable position, raiding margins of the empire became less attractive.
3)The nature of Attila's rule was personal. Once died, the sucessor(s) had to begin again and rework the "political" ties.
Now, maybe one of Attila sucessors COULD, because of butterflies, do better than OTL and create a more stable kingdom at the marges of Roman Empire (as did the Gepides by exemple), in Pannonia if they could do well enough.
That's probably the best way to have a surviving Hunnic state, at least for more than 50 years.