You do understand that DASH also has 2 currencies on the network? The mixed coins and the unmixed coins.
It's pretty obvious that DASH has fungibility issues. You need default mixing to solve this.
That's apparently the plan for Evolution. I guess that stemmed naturally from the quorum system.
We've made some massive progress on the DS side and the next version will support network wide anonymity, that doesn't obscure UTXO like cryptonote, is instantaneous, has no bload, has blinding and other identity protection built in. We won't require a name anymore for the service, because it's not a service, Dash will just be anonymous by default.
if darksend is very slow and costs fees, people will probably not mix as much as he hopes.