A recent article in Computerworld listed ten promises or "undertakings" Oracle made to the European commission about MySQL in an effort to gain that body's approval of Oracle's proposed merger with Sun. The problem is that the promises have a lifetime of 5 years, after which Oracle could renege on all of them. That is exactly what some critics, me among them, think will happen - I don't see what Oracle has to gain by keeping MySQL around.
This exposes a broader problem with the programming language PHP. Many Web sites are built using PHP and make specific calls the the MySQL library. In most modern programming environments, calls are made to a database "abstraction" layer that isolates the application from a specific database. Developers who use such a layer can switch horses by changing a few lines of code to invoke use of a different database system. PHP has a layer called PDO that does this.
The beneficiary of the uncertain future of MySQL may be the highly-regarded PostgreSQL. Unfortunately, while almost all Web hosting companies provide MySQL, very few offer PostgreSQL as an option.