When you say crypto does it mean bitcoin only or any coins too? If you are referring to bitcoin then I think it is impossible because bitcoin has a lot of investors and it is growing every day. Bitcoin is very successful for many years now and it has established it's name already. I know anything can happen, it's the reality but if the price will go down it won't go as low as zero. On the other note, the only coins that I see that would go zero are those shitcoins who did nothing but just to ruin cryptocurrency image.
Even if the governments rolls out their own digital currencies we can't take the fact that bitcoin will be on top of that in terms of investment but in the field of daily payments and usage it will totally crush bitcoin for it has high transaction fee and long waiting time but bitcoin will still not reach zero because of that but the shitcoins will surely vanished from the market.