Hmmmmmm what does that underlined part says?
In short this will never ever happen.

Because that would mean more than 1 login at the same time. More than 1 game played at the same time on the Steam account by more than 1 person at a time.

Steam was not made for this and never will be made for this.

How do I enable Family Library Sharing on my computer?
To enable Family Library Sharing, first be sure you have Steam Guard security enabled via Steam > Settings > Account in the Steam Client. Then enable the sharing feature via Settings > Family, (or in Big Picture mode, Settings > Family Library Sharing,) where you'll also authorize specific computers and users to share.

Is there a limit to the number of devices or friends I can authorize to share my Library?
Yes. You may authorize Family Library Sharing on up to 10 devices at a given time, and for up to 5 accounts that may then use your game library on any of your authorized computers.

Will I be punished for any cheating or fraud conducted by other users while playing my games?
Your Family Library Sharing privileges may be revoked and your account may also be VAC banned if your library is used by others to conduct cheating or fraud. Additionally, VAC-banned games cannot be shared. We recommend you only authorize familiar computers you know to be secure. And as always, never give your password to anyone.