Last season while discussing the McKeon rule, this was brought up but fell by the wayside amidst all the arguing. I liked it then but I took it too far with the whole stick to your position thing. Personally, I like position flexibility within reason (i.e not an exploit), but starting in 1991, no more WR at DB or vice versa.
Between last year's discussion and the current discussion, I have determined we have enough support for this, we don't need to vote.