Lewis Cummingham posed the question, "What would you add to Oracle?" in his blog. He purposed the ability to support multiple languages within the database. Thinking completely out of the box, I would enlarge that concept to include support of other database vendors' environments within an Oracle database. Instead of just allowing users to hop from Oracle over to another database vendor's database via a "gateway", why not just put that other vendor's database inside of an Oracle database. Oracle could experiment with MySql first because they own it.
I know that this is "Pie in the sky" type of stuff, but you never know.