As with any link on any website: if the link no longer exists, the link will be broken, dead, etc.
But don't worry: if ever the jquery library would go offline, there are many places where you could download a copy from.
Alternatively you could start using a local copy of jquery.

As with any link on any website: if the link no longer exists, the link will be broken, dead, etc.
But don't worry: if ever the jquery library would go offline, there are many places where you could download a copy from.

Alternatively you could start using a local copy of jquery.
In that case you will have to manage/download upgrades yourself.