I don't think one or more exchanges set the value (community members that use the exchange platforms do) and the disappearance of one or more (or all) of the exchanges has any affiliation with actual worth or valuation.  Instead the disappearance of one or more *coin-holding community members have affiliation with actual worth or valuation.  Putting pressure or blame towards those one or more exchanges (which are not the source for the items exchanged) seems like a misdirected effort.