Yes, the cryptocurrency bubble will burst because trust embodied by any currency is, and must be, discriminatory. But to predict when greater-fools will recognize valuations do not carry intrinsic value is another matter. Humanity is prone to grandiose and long-lasting hallucinations, long-lasting even in the face of overwhelming evidence and reason against their suppositions.
Cryptocurrencies fail to meet the essential criteria of the supposed merit of money, the distribution of trust only to those who deserve it.
The merit of money shall not be evenly distributed because our contribution of intrinsic merit is not evenly distributed (courtesy of the unique sequencing of our DNA). Hence, a currency that circulates the merit of money uniformly is in direct conflict with the evolutionary integrity of humanity.
When the bottom falls out depends on too many factors to predict with any reasonable degree of accuracy, not excluding the unpredictability of greater-fools. Anyone believing in this manmade fairy-tale of financial voodoo is deserving of what comes out of it.
When I talk with you in person, I can remind you of a recent large-scale wine-buyer debacle, one that made one of the Koch brothers lose a lot of money, eerily similar to why cryptocurrencies will fail, with a cunningly disguised scheme of trust.
So, here is my surgeon-general warning: do not sink money into cryptocurrencies you cannot afford to lose.