Docusign integration in 7.2 only provides a way to void an Envelope/document or send out the Envelopes to collect/request the signatures.
To my knowledge, CoSign is an on-premise electronic signature appliance from Docusign that allows the users to Sign the documents. Since the current offering of Docusign integration only talks about collecting signatures, i believe, there was no scope for cosign here.
CoSign central seems to go well with Document authoring tools and content management/authoring workflows such as sharepoint.
So, one might need to play with Pega integration with Sharepoint that has cosign integrated in it, i guess.