For publishers this was a simple feature that help them understand if they are on track to hit expect level of page views and hence ad inventory for a given month.
I agree, this is a very handy feature that is missing in version 14. It would also be great if the forecast could be included in a dashboard, and updated daily.
Archiving due to age and relevance. If this is still something that is desired while using the latest version of Analytics/Analysis Workspace, I'd highly recommend creating a new idea and linking this idea there. Thanks!