FCoE was going to take over the world....
....it hasn't, and I've pretty much only seen it used as described by Enrico to reduce spend in chassis (not very often as ToR).
That's not how it was being positioned - it was going to be the protocol that took over the FC world. It hasn't even taken over all the networking in chassis based compute (where there is a potential case to use it).
Saying that people have bought it and therefore it can't be dead is missing the point - a lot of people bought Betamax (and some even bought HD-DVD). Did that mean those didn't turn out to be technical cul-de-sacs without a future?