Will all the alt-coins disappear ? I don't thinks so but I think that there will be a massive cull. To survive an alt-coin needs to have some kind of USP and I do not believe that all the 2116 coins currently listed on coinmarket cap all have some unique USP that will power them to success. IMHO they are all correlated to BTC and the longer BTC remains in a bear market or just consolidates at low levels the more alt-coins will disappear.