Nothing will happen to bitcoin here, in fact maybe it could bring more money to bitcoin ecosystem for all we know. So I don't think Libra will have a negative impact as far as the market price. Investors would simply go and shift their funds to a private, consortium wherein it is centralizes and all your private data will be in their own crypto. Crypto investors are not that dumb, on the contrary they are getting smarter now that's why they are not bother by the supposedly challenge from Facebook's Libra.
The problem for me in looking at this argument is that we only need to look back a year and a half ago at what happened to the crypto market when the ecosystem had more money flowing in. Sure, people were buying Bitcoin but only to invest in hundreds of ICOs (and the same also happened to ETH once ERC20 ICOs started becoming popular) and that didn't end up too well afterwards, did it?