It's kinda inevitable that there will be one or several big crashes coming up. However, it's far from trivial to say when. Perhaps when the market reaches 200b, 1t or 10t - who knows?
The technology has a lot of use cases, meaning even a crash or two won't eliminate the market. But it will kill a lot of the altcoins I'd wager.
The dot-com bubble didn't result in the internet becoming worthless, just a bunch of the companies trying to profit from it (the bottom lot)
I totally agree with this statement. Even if a lot of coins are not scams and look promising, only a few of them will get mainstream and survive to the bubble explosion. I only invest in coins with a wide span of potential and not limited to a single use case.