Libra has raised fears about the future of blockchain mainly because it goes against everything the community wants and believes in: decentralization.
Facebook could ultimately create a massive closed-loop revenue model from ads, digital marketplace, to payments. Do consumers want to bet on the status quo of existing monoliths?
https://elixxir.io/blog/is-libra-the-future-anyone-wants Libra is another type of stablecoin according to source, but there are lots of stablecoins in the market, and they are not a threat even to world financial systems, maybe it can help to ease the transactions unlike using the banks which require higher fees and a transaction time.