Recently confirmed by @XboxSupport on twitter, if your account has been banned you will lose the license to any games attributed to that account.

If your account is banned, you also forfeit the licenses to any games that have licenses tied to it as listed in the ToU. ^AC

— Xbox Support (@XboxSupport1) June 14, 2013
This news comes as yet another blow to the perceived attack on gamers. Not everyone is banned fairly, so this could become a huge problem down the road.

When asked about a hacked account, this was their response.

Ensure your account security features are enabled, and security proofs details are correct. ^ML
— Xbox Support (@XboxSupport1)

June 15, 2013
We have reached out to make sure that this only applies to digital games and not your disc copies. If so then it is crisis averted.

Their response is to be expected, with no real confirmation one way or the other.
@snickelsox We don’t have any specifics on that at this time. More info will be available in the coming months. ^AD

— Xbox Support (@XboxSupport1) June 15, 2013
What does this mean for Disc Games. One could argue that they should have a clear “no” on this if they intended to let banned players keep their disc licenses. But, they could have just not made up their minds yet. So we will wait and see and hope for the best but, given their recent track record, prepare for the worst.

I also asked if Netflix and TV functionality would be available to banned players. They responded in another ambiguous way. ( I neglected to clarify if this applied to Xbox One or Xbox 360.)

Those features would not be available on the Xbox 360, as for the Xbox One we don’t have those details at this time. ^AD

— Xbox Support (@XboxSupport1) June 15, 2013
I have also reached out to Xbox officially, rather than their twitter support, for comment. We will update if/when we hear back from them.

[update 2]
There has been reference to the the Terms of Service that Xbox users have to agree to in order to use the service. While the current terms are specifically for Xbox Live on Xbox 360 andnot Xbox One one can infer a few of the possible guidelines that the Xbox One will use when it comes to your rights.

Section 1.7 is the directed response which states:
We may change the Services at any time, for any reason or no reason, and we may also cancel or suspend your ability to access the Services if you’re in breach of this Agreement. If we cancel your Services account or your credentials, your right to use the Services stops immediately, but you’re still required to pay all charges already incurred through that account.
But reading a bit further down into article 1.12 we could see the way things could change. Games are considered more of a service now and unless you work within the confines of the Xbox One market place, your game could be considered unauthorized software.

You can’t use unauthorized software or hardware to access the Services, nor can you modify an Authorized Device in any unauthorized way (e.g., through unauthorized repairs, unauthorized upgrades, or unauthorized downloads). You agree that we have the right to send data, applications or other content to any software or hardware that you are using to access the Services for the purpose of detecting an unauthorized modification and/or disabling the modified device.

You must not attempt to disassemble, decompile, create derivative works of, reverse engineer, modify, further sublicense, distribute, or use for other purposes the Services, any game, application, or other content available or accessible through the Services, or any hardware associated with the Services or with an Authorized Device. If you do, we may cancel your account and your ability to access the Services, and pursue other legal remedies. We may take any legal action we deem appropriate against users who violate our systems or network security, this Agreement or any additional terms incorporated or referenced in it. Such users may also incur criminal or civil liability.
At the moment the Terms of Service can only help speculate how the Xbox One will handle banned account who own games, bought either new or used. Nobody, outside of a few higher-ups at Microsoft, truly knows how this will all works yet. Let us hope thatthey can pull together a message quickly to address this potential problem.

[update 3]

Well that was quick. According to @XboxSupport1 the original tweet was “intended” for the Xbox 360, not Xbox One. While this would not be the first time Xbox Support said something in error, it would also not be the first time they revealed something before it was ready. I personally hope this was a simple mistake, but that leaves a burning question in my mind. What about all the other tweets?

There was some confusion here. That tweet was intended to refer to downloadable games on the Xbox 360 actually. ^AD
— Xbox Support (@XboxSupport1) June 15, 2013

Are they having a freaking laugh