That workflow will happen inside of Analytics but will notify the user throughout the marketing cloud. So, for example, I set up a project in Analysis Workspace and share it with my colleague who manages testing and optimization. She logs in to Adobe Target and sees a notification that I have shared a project with her. She can click on that notification to go over to Analytics to work with the project there.
I don't think we'll be making any further investments in pushing items to cards and boards in the Marketing Cloud, at least in the short term.