The great thing about Open Source is that despite proprietary vendors best efforts, they can't control the market for open source. When I first joined MySQL AB years ago, industry analysts estimated there were over 12 million MySQL database servers running. Which is why MySQL has been considered the most popular database. Now conservative estimates are now at 80 million MySQL database servers running.
MySQL is also the most popular database for the cloud. All major efforts you see from companies like Amazon and Google, are all supporting MySQL as the database engine behind the cloud. Companies are seeing that if it works for some of the biggest Cloud companies in the world, it can work for them also. A friend of mine (Tom) refers to MySQL as the "secret sauce" of the Internet and the Cloud. I couldn't agree more.