Why will Oracle win?
The primary customers that Oracle has (multinationals and governments) are implementing strategies to prevent vendor lock-in. With the acquisition of Sun, Oracle can provide a vertically integrated stack that is essentially vendor lock-in free. It has a Sparc architecture hardware (which is open source), it has Solaris (and thus also OpenSolaris) and has the open source database MySQL.
So in essence, customers can buy the open source stack from Oracle. They would be paying Oracle to put everything together in a nice package and making sure the stack works. Yes, from installing the servers in your rack, all the way up to and including the application level.
However the customer would still be able to sleep at night, since if Oracle fails or the customer has a need that Oracle cannot give them, they can just call any other (local) software developer and pay them to build the functionality. This is possible (and cheap) since the source code of the stack is completely available.
The customers can then also decide to give this functionality (they paid for) back to the community. This might look like capital destruction, but remember that software needs support and updates which are more expensive in the long term.
Releasing the source code will ensure the code get's improved over time and thus making the stack better. You prevent buying a support / update license from the company you paid to give you the functionality. You will pay less for updates, since other people that will run the same stack will have the same problems as you and thus dividing the total cost of repairing the software.
Oracle understands that companies don't want to be locked-in, but also do not want to spend a lot of money on finding out what to buy or get and integrate everything. Customers want to be vendor lock-in *proof*, for the rare occasion that they need to switch. But customers will mostly want to focus on their own value proposition. Customers do not want to focus on things that don't add value or are not a strategic advantage for them (i.e. the software stack). Using open source ensures a reduction in cost in this part of the customers value chain.
Oracle thus obtained a sustainable competitive advantage. With Oracle customers can "buy" a complete open source stack. An offer that Microsoft will never be able to provide. And Oracle is protected from "me-too" products, since they have a huge network of sales people and support vendors. All of which have a warm long lasting relationship with their customers.
So Oracle's advantage is in the *capability* (not the stack!) to deliver functionality for customers by combining open source hardware and software components with a world-wide enterprise level support. It's nowhere written they need to provide the entire integrated stack in a nice DVD image. As long as they release changes to the *separate* open source projects they are in compliance with the open source licences.
This capability is hard to compete with in this area (government and multinational) of the software market.
(My apologies for offending people by using all those business buzzwords and lingo, but it's for a good cause ;) )