I don't know, but I'm guessing that the RAM will still be user upgradeable. The reason? The case has not changed, so there is no need or advantage to changing the RAM slots.
I know the Apple site says "only upgradeable at the Apple online store", but I take this to mean that if you want Apple-branded RAM, then this is the only option. They are hardly likely to recommend you buy 3rd party RAM.
Let's see!