If all goes well for Facebook's Libra cryptocurrency (in terms of regulatory compliance), then it may very well launch it's own ICO instead of an IEO. Facebook is still a trusted company worldwide, despite the latest privacy scandals. The inception of the Libra blockchain will greatly transform our economy in many ways that were never thought possible before. While it's going to be extremely centralized, and audited by the government, it will serve well as an alternative to physical cash (Fiat).

However, Libra will never threaten the existence of popular cryptocurrencies like Bitcoin and Ethereum since it's a completely different thing. It's like comparing apples vs oranges. Libra will become the world's next-generation Fiat (if approved by governments worldwide), while cryptocurrencies like Bitcoin and Ethereum will become the alternative money for the people. Being centralized has its benefits such as lower fees and higher speeds, but it lacks censorship-resistance and resilience. On the other hand, decentralization solves these problems but it's unable to process transactions at high speeds while maintaining costs as low as possible.

Nonetheless, Facebook's cryptocurrency will bring a greater level of Blockchain adoption among people in the mainstream world. Of course, it'll need to have the approval of worldwide governments in order to become a success. Otherwise, it'll become vaporware over time. Just my opinion