This makes me think it's definitely more like family sharing. You have a shared library, with a certain number of other people on your account, with however many active licenses you add to the pool. You access the game by verifying via the internet, and only one can access it at a time. I'm guessing there's a countdown after the main account logs into it, for you to save/quit.
But maybe you'll be able to create individual libraries that you share with smaller groups. So many titles with your bother, so many with your friend, so many with your brother and your friend, etc.
It'll be close, but Romney has the momentum.