It is finally here.
You can now connect to a Planning Analytics on Cloud Data Source from Cognos Analytics on Demand.
From Manage -> Data server connections select IBM Planning Analytics
Select Integrated Security as the authentication method
Enter your Planning Analytics database host
Set the HTTP port number to -2
Save the connection
Please note that that users and groups are separately managed and configured in CA on Demand and PAoC This means that security groups in CA on Demand can NOT be used in PAoC.
This connection is only for Planning Analytics on Cloud from Cognos Analytics on Demand
Read more about this here
For Planning Analytics on Cloud and Cognos Analytics on Cloud Hosted integration read more here
and see some configuration details here