I don't think crypto as a whole will go to zero value, but I think there are some crypto coins that will definitely go to zero because of no development of the project, investors will pull out their money if the certain project has no improvement.
they will not be zero but will go down to a minimum. there are always people who forgot about their coins or simply they don't want to sell at the prices that they see on the exchanges. that's why do not worry - you will not see 0 