I just farted
anything with quality or rarity , preferebly both
If people knew now, they wouldn't become valuable since everyone would save them so they wouldn't be rare. One guess is popular toys, like new and in their box.
Only the highest quality workmanship will survive the years and ever-changing fads. Original design would become desirable. Look for handcrafted designer-original furniture & take excellent care of it.
Certain fad items may become collectibles - e.g. certain scarce Beanie Babies, original Barbie dolls & outfits from the 1950s, Beatles memorabilia. But these must be mint-new, in their original packaging.
BY THE TIME, YOU WERE DEAD ALREADY, WHY BOTHER TO KNOW.
I once saw an antiques shop on Cape Cod that was named MY GRANDMOTHER HAD ONE OF THOSE BUT SHE THREW IT AWAY.
So ask your grandmother for all the things she wants to throw away. Those are future antiques. Resist the urge to throw them away. Also resist marrying anyone who wants to throw them away. Pray that eBay (and you) will be around 70 years from now. You'll be rich!
Steering wheels and internal combustion engines.
The essence of vintage objects is artistry - design that impresses us as much decades or centuries later. Raw technology rarely makes the cut; we value Model Ts today not merely because they are old but because they are rare. For all that you can buy a car that is nearly a hundred years old for about $10-000-$15,000 but if you want a Jaguar e-Type that is half that old you will pay nearly ten times as much. A Ford Falcon sells in the price range of a Model T. Artistry at work.
Around the turn of the century I read an article, possibly in USA Today, that looked into the twisted path we take into the future. It suggested if we were to realize the potential of personal computing as the technology was beginning to take off we would invest in the leading personal computer company of the day: Commodore. Today you can pick up the iconic Commodore 64 with a disk drive - a $300 value in its time - for $10. No artistry.
Your guess is as good as mine.
But if there was some way for foretelling this, the opposite may occur because people would then stock up and save those items believing that those items would become valuable in the future. If many examples survive, they remain common and not as valuable.
Furbys, robotic vacuum cleaners, original IPhones.
Things that are fragile and won't last well.