Can't be that bad
Its been in use for 20 years, and is *very* widely used with easy access to all the components, and yet they've only just got around to cracking it. And even then it isn't trivial. And it needed help from a Wiki entry. (Who posted that by the way - a rival supplier?)
For cars it'll still be easier to just steal the keys, as this will get you around all the security systems not just the KeeLoq part. (Immobiliser transponder is usually a different system to the remote locking transmitter, so wouldn't be touched by this)
As for building security, if your only security relies on a chip card then you aren't trying hard enough.
I'm sure people will use this for bad things, but I'm not sure the threat is particularly severe - at least for now.