I don't know why they ever used touch screens in the first place. The election officials fell for a sales pitch and a slick gimmick.
People who are blind can use touch-screen machines without assistance (and thus without letting anyone know how they're voting). On the other hand, even places that use optical-scan ballots could handle blind voters by simply having a touch-screen machine that places marks on a paper ballot as directed by the voter; the paper ballot would then be counted the same as any other.