>>If all they can respond to is blood activity in one or another part of the brain they will never be able to make a genuine, parseable command interface.<<

Being that this is just in its infancy, it is impossible to say at that this time that they will never be able to accomplish this or that. In all likelihood, they will. If the interface shows too much promist to simply discard it, they'll work on it. It has to be the direction things are going because the purpose of technology is to make our lives easier and what could be easier than something happening because you willed it to happen?

It is the ultimate in convenience and ease and every new device tries to simulate that as much as possible. It is inevitable that we will one day have the real thing--and this is the start of it.