The ram is not the only thing vital to change, there are many other components that are under development. Why would people think that the Ram is going to change when they already publicly promised it. Breaking a promise would only hurt them, and they are out to improve their image with developers and possibly gamers.
The only thing I can see from this announcement is that they wish to tell their competition that they can still modify their console to be competitive with any changes in technology and trends. So Microsoft better watch what they reveal because Sony can come up with some way to "fight" against it. (It did say that the company is at war)
Ya, realistically neither Sony nor MS will be able to change anything major in their consoles unless they want to delay their release, which would be a big mistake.
But, I agree that it seems more like a stunt to make it seem like they can change if they need to counter MS.