From all guesses, Nintendo will probably give up more of the space, but probably don't want to end up in a situation like Sony where they didn't have RAM to add a feature the competition implements.
For now, developers already have a little over 2X the usuable ram of the PS3 and 360, so Nintendo doesn't need to be in a rush to slim down the OS when devs are still targeting 512MB systems.
They did the same with 3DS, they freed up some RAM for developers post-launch from their reserved system RAM.
There's also the potential it's to be used for multitasking or suspending a game and starting the browser, etc.
Don't be surprised when MS and Sony have a ton of RAM relative to the rest of the console set aside for the system in their new consoles as well.