I don't think so. Twitter has evolved into a communication tool that doubles as an alert system for some uses. Live feed is less voluntary, since it's automatically recording and publishing what you're doing. The appeal isn't JUST being having updates on what's going on, it's letting people interact with your actions, to collaborate from multiple mediums. LiveFeed seems limited to what you do on Facebook, Twitter lets users define their own activity, and FriendFeed scrapes everything.
Where's the appeal, then? I think saying this will "kill" anything is incredibly premature.
Facebook is also a walled garden. To have access to the feed you have to sign up and be a friend of the person. With Twitter, the default is to have a public feed.
I think the main difference is that with twitter its a one way following. You can follow people and they can be completely unaware. With facebook you have to have the two way yes we both consider each other 'friends'.
To actually beat twitter/friendfeed they would have to allow a 'stalker' relationship. So you can stalk someone without being their friend.
Where's the appeal, then? I think saying this will "kill" anything is incredibly premature.