To kill off the MacBook completely
I love the trackpad rumors as I love the iPad Pro, but event though the iPad sells far more units, the Mac still generates more revenue as the margins are better. Apple would be crazy to kill the Mac for that reason alone, but for many many other reasons as well.
No need for anyone to feel insecure about the Mac because one platform is getting better text input support. These are two completely different demos that use either as their primary computer.