At the moment the Nort crew has 12 members, meaning that there is one vacant seat (it was supposed to be Sora's, but you know what happened). If Master Xehanort isn't bluffing, Terra is a darkness. This means there are 6 confirmed lights: Sora, Riku, Kairi, Mickey, Aqua and Ventus. What I do believe is that the X-Blade will be forged, but the fundamental requirement is that there must be 13 darknesses and 7 lights. This is likely going to be the final scenario, the infamous clash that is supposed to be occurring. Sora & co. will try their best to dispossess Terra from Xehanort and they will be able to. The thing is that we would end up having 7 lights and 11 darknesses which is not what it should be. Therefore at the current state, all we can say is that we've got to expect a few plotwists, like it or not.