As everyone knows, WordPress is shackled to MySQL because of the way Its database class is hard coded with calls to MySQL specific functions. This was fine before, but there are some things we must consider when deciding if this is still a good idea today.
One is the resent take over at Sun Micro Systems. Sun created and maintained MySQL, arguably the most used database system in the world. Oracle, the manufacture of the close source, grossly over priced (a personal opinion,) Oracle database system, wanted to take over this very large market share that MySQL had acquired over the years. They did just that; Oracle now owns Sun, and is actively dismantling the great and many open source projects Sun had created, and maintained.
Its very sad indeed. Now that Oracle own Sun, and MySQL along with it, It can be expected that MySQL will be slowly killed of by the new administration due to the fact that it can be predicted that Oracle will try to force database end users to "make the switch" to Oracle. Oracle has no incentive to maintain MySQL.
We have to, I emphasize, we must implement a driver system for our database class. If we do not I fear we will loose WordPress as MySQL drags it to the depths of history. Don't laugh, history has shown that very widely used software can disappear.
If we implement a new driver based system, where we can map database functions to generic functions to be used within the database object. Switching the driver simply remaps the $wpdb functions to different native database functions defined within the new driver.
This also allows WordPress users to create pluggable WordPress database drivers for virtually any form of data storage.
We cannot afford to stay tied to MySQL, we need to create a driver layer in our next release. It should have been in WordPress 3.