Microsoft has confirmed that if you have an Xbox Live Gold membership for your 360 it will work on your new Xbox One.
Once you’ve paid for that membership, any accounts on the Xbox One can login. So you’re essentially paying for the IP of that console, rather than the online account. If you and your son have two separate accounts on the Xbox One, they’re both connected via that one Live Gold membership.
We’re waiting for a catch – but it looks like this is a dream come true for student houses.