I think that Libra coin is just another altcoin that will help to spread the knowledge regarding cryptocurrency. Since this is Facebook coin and many are using Facebook around the world, many will become curious about it and will do some research on it then they will decide if they will invest or not.
Libra will help to spread cryptocurrency awareness throughout the world. At least that is the good thing so far from libra to the crypto world. Meanwhile, we don't need to worry about Libra being a threat to the existence of bitcoin. There are already lots of alts out there and bitcoin is still unshakeable!