New partner community coming. Most likely built on Salesforce Communities.
I do not think this is going to replace the portal. Rather think of it as a 90 Minds type group for partners to figure out who to talk with at Sage and where to get collateral, share sales best practices, interact with Sage sales reps. '
In the video, Marc talks about cases but I do not think (could be wrong) that he means a tech support case. SFDC has a feature called cases which can be used to track a lot of questions and open issues and I am guessing that Sage will use cases for partners to submit questions on pricing, etc.
Hard to say exactly what this will encompass except it definitely seems as if it's a MySageSell replacement. I do not think you will submit support cases or look up customer records/keys inside of this. I expect it to be mostly a partner collaborative tool built on top fo Salesforce Communities. Public and private collaborative groups. At least that's the most that I've been able to make out of this.
Sage has been advertising for internal SFDC people for several months.
http://erplife.com/2016/08/24/sage-provides-partner-community-video-update/