I think one day the weak projects will collapse. Robust projects of the market like ZEC, such as XMR, can survive after such a time. It sounds like a solid project to me, MONERO.
Such an outcome is also possible. But with this outcome many will lose their savings in the crypto currency. Smart investor stores more than 80% in a reliable crypto currency.
If it's a widespread crash, like the dotcom bubble collapse, it won't matter what you're holding, amazon had the same fate as pets.com--being invested in a reliable cryptocurrency only means that it will win back the losses when the market returns. If you can correctly time your exit, you'll be able to buy more of the better cryptos, so it's not necesarily a bad thing.