I think the late 80's early nineties crash in the classic car market happened in a completely different climate to what we have now.
I was earning my money in that exact field at the time and witnessed it first hand, before resuming with my engineering company when the bubble burst.
I think the likes of E Types were incredibly over priced for the time and people knew it, it was the guys who had 40 or 50 of these (and similar) in stock at the time that were crucified by it. Those prices were in reality higher than what they are now,
As for now it's a different business, the classic car market is nothing like what it was and has spread massively in the in between years.
We had maybe 2 National classic shows a year and a few exclusive auctions and nothing like the exposure and interest the market has now thanks to the internet and social media. It is also now not just exclusive for a certain small minority, it is enjoyed and participated in by millions world wide.
Also the days of high savings rates and expensive mortgages are over, I believe for good, and people who come in to money, probably people who are first to inherit in a family wonder what to do with that money..........buy 100k of premium bonds for him/her and their spouse or maybe buy a classic and enjoy the vibrant social scene that can come with it.....if you want it.
I think the market is big enough to survive with ease, if it were to crash it'd have well done so by now.