The Microsoft Business Center was launched worldwide on 16 May, 2016. This is the new portal for MPSA users and while it looks different at first glance, carrying out tasks such as viewing licences, downloading keys, and managing SA benefits is the same.
There is, however, a new URL (businessaccount.microsoft.com), but existing credentials will still work, and we’re told that future plans include the ability to see purchases made through other Volume Licensing agreements – hurrah!
This FAQ is a good overview document: http://bit.ly/1TMOhSm.