To clarify, I'm certainly not approaching this from a personal ethics standpoint. It is I suppose a question of social service authentication elasticity. Will removing twitter at the outset significantly reduce my sign ups to the point that it would be smarter to deal with the repercussions of losing API access in the future? Or are most users not so sensitive to which service they use to sign up for something, such that if facebook is the only option, I can guarantee a consistent experience for all users going forward?