Also your plan requires that everyone work primarily on laptops (unless you expect to lug your desktop and monitors to a cube when you need to concentrate). And you've basically allocated double the space (cubes for half the team plus a room big enough for the whole team). Why not just cut the space up more efficiently and give everyone a private space?
This seems like a bad deal for everyone. Workers still feel like they have no privacy and are constantly distracted, and the company is paying for a lot of extra space.