I think electrification, and gentrification, will continue to push the prices down on our cars. The high end cars may escape some of the downward pressure (think Boss429, 65 GT350, etc), but it's already arrived.
I was at B-J in January of 2019, COVID had yet to impact the economy. Boss 302s, z-28s were selling $25k off of pricing just a few years ago. I saw this beautifully restored 53 Chevy, obviously no expense spared, cross the block for $16k. You couldn't have painted the car for that. There were many, many others in similar boats. The generation that's into that 50s era car is on its way out.
My generation (Gen X), seems to like 60/70s muscle, likely because they filled the parking lots at High School back when you could buy a Boss 302 for $3000. And the cars are cool. Boomer likes the same because it takes many of them back to their first new car, and the excitement that surrounding automobiles produced in that era. Like my dad who still owns the '67 Mustang he bought new in '67. As the Boomer generation departs, more cars are left on the market. Gen X will scoop up some interesting cars at bargain (for today) pricing in the future. Millennial, has much less interest in the 60/70s cars because they aren't touchstones for their generation.
What it tells me to do, is drive my 69 GT350 now. I already know its past its peak value, and I aint ever gonna sell it. Friend of mine with a '68CJ car he's owned since the late 80s is doing the same. Hell, he's putting the throttle down and just built a 470 cube FE with a Tunnel Wedge and dual quads, and is converting to a 4sp. He's looking for fun driving time ahead.
Enjoy them now, while we can. If your car is an "investment" to you, then you might re-evaluate your position. If its for the love of the hobby, you're in luck. Fun times await. Some of my friends spend more on golf/booze/? what have you, and they don't care about the depreciation of the liquor or golf clubs. Just a point of view.