Personally i will welcome both as both of these coins will add to the total market cap of crypto market that will definitely have a boosting impact on the market especially when a wholly new people will enter crypto market through libra or amazon. Secondly i think fb and amazon are 2 very different business niches fb is truly global and amazon is just available in a dozen big countries only but yes amazon has billions in transactions so it is huge as well for me it will be great time coming for crypto market.
Yes, they're both welcome in the crypto world but remember that it's a business, there will be always a competition. Everything that has been created literally adds a good factor for the community, we know that but It will be always one that will reigns.
Facebook is only available in some countries especially in Asia because they have a different social media platform that is using. Amazon was also known in some other countries and have a good purpose for them, buying some rare stuff that can be bought internationally and through amazon, you can get it.
They're both have potential and have different platforms but when it comes to cryptocurrency, it's all about the money so it will cause a good competition for both side.