There's so much wrong with this I don't even know where to start....
1. Rumors say 3GB is reserved for OS and 5 for games. Seems a bit much to me so having the OS memory reduced to 1 or 2 GB is very likely.
2. RAM isn't everything. Based on Xbox 720 rumors, it is a generation ahead of the Wii U in terms of tech. Wii U won't be able to run games built for next-gen systems. It's already not getting UE4 and many other engines that will power AAA games.