I consider myself a realist (some would say a pessimist, I'm sure)...
Assuming that those of us thinking about this issue / asking the question still have another 20 -25 years of life in them, and are not contemplating selling out in the very near future...
There's a 75% probability (IMO, and just a figure off the top of my head) that it's all going to either go to the landfill or be sold as a lot for pennies on the dollar.
Why? Because TODAY the pool of hobbyists / interested buyers & sellers of high end audio equipment is already half of what it was 20 years ago... 20 - 25 years from now, it will be 10% of what it is TODAY. The market will simply dwindle down to almost nothing, like it or not.
Next factor, the overwhelming majority of people left in 20+ years with any interest at all will be in 3 categories:
1) the remaining old fogeys like us who grew up with this equipment but who, for the most part, will be too old / too poor to be in a position to spend exorbitant sums of money on purchasing your estate equipment. They will be too busy clinging to their own hoard, all the while proclaiming "I don't care what anyone says - I won't selling for less than I paid for it - and if I can't get my price, I ain't selling!;
2) Wealthy individuals of any age who - if they have any interest at all - will be much more likely to simply purchase new, and have little to no interest in what will be seen as antiquated equipment by then;
3) A very small slice of younger people who might have interest in 'vintage audio' the way some of us do today. A further negative will be that the pool of people with the ability or qualifications and equipment needed to REPAIR / RESTORE electronics will be even smaller than it is today... again, probably by a factor of 5 - 10.
My personal opinion / advice for those who got into this at least in part as an "investment / for retirement"...
Start planning for a sale within the next few years, max. The longer you hold out the less you will get for your gear; and the greater a chance that it may literally just be thrown away.
The silver lining? You will be dead - and will not know, or care, by then...

