I also don't see it as a threat to bitcoin because people knows it's the new gold that is just digital. And facebook's coin is not a real crypto and just pretending to be. Also, a lot of people in the crypto community has expressed their hate on the Libra coin and they don't like it. The privacy is going to be a big issue on Zuck's coin and internet users are starting to get the awareness that they should always take care of their private information.