I'm guessing that when mind reading comes it will be more more of a machine learning exercise based on analysis of speech, vocal inflections, visible features,

I'm guessing that when mind reading comes it will be more more of a machine learning exercise based on analysis of speech, vocal inflections, visible features, and previous actions than a portable EKG machine with wires on the scalp. See Poe's detective Auguste Dupin, in, for example, "Murders in the Rue Morgue."