Current campaign is useless when completely finished although it got updated. After the 4 bosses at the end it’s basically done. A way we could use campaign for more higher players and lower the is adding a rotation of dna that you have to battle for. ( similar to the jwtg concept when max level is reached.) it gives more reasons to come back to the campaign and level for lower players.
The range can be to rare to epic dna and some times could be legendary dna. It would be balanced out on how much dna you based on difficulty.