I was thinking, that in birth by sleep, that since you have no partners,or at least at hasn't been confirmed yet that you have team mates, what is going to happen with the drive system. Then I had an idea, when nomura was talking about some sort of growth system in the game, I thought that maybe as you progress through the game, and as you grow stronger, terra,aqua or ven will be able to transform into their armor, like we saw in the bbs trailer and that will kind of replace the drive system. just a idea anyway