When will it happen? No one knows. It could be tomorrow or next year or possibly not.
Why do you want that to happen? Is there a big reason why you want the altcoin industry to crash? Ain't it good for the companies who own it if the value of their tokens will keep on rising? I only rely on Bitcoin's price and if it's in bear, just a small amount of altcoins will survive it.
I want to buy more alts but at cheaper prices.