The real fact on the ground is that bitcoin would continue to fluctuate despite the many speculations. Beyond 2020 and the successful implementation of Libra as a cryptocurrency that is attached to a popular brand as good as Facebook inc, bitcoin and all other cryptocurrencies would be affected by price volatility.
If you take a look at all the financial market can you point to a stable market and if it is a stable market who will be investing in it and what benefit do you get from a stable market and the other part about Libra, you need to wait and see whether Libra will be released or not as the regulatory pressure is increasing and it is highly unlikely they will release it peacefully.The news regarding Starbucks is quite huge and its possible impact could be significant to the market. It's one of the most popular premium coffee bars and has a great market of variety of people from the upper to middle class.
Since star bucks is accepting and selling bitcoin now everyone will be sleeping and drinking coffee in star bucks 
. On a serious note it is a step towards major adoption in the market.