I have also pondered this and the one car I come up with is the Subaru WRX, but I can also agree with the Toyobaru twins, the second generation Fiero, many Corvettes, and the S2000. The problem will be in finding examples of any of these cars that haven't been "boy-racered" to near death especially the WRXs.
One car that might become collectible is the Toyota sports car that came out around the same time as the S2000. As these are so weird looking and so few were sold they may become collectible.
Miatas may be collectible in that many will be junked as there are so many of them now. The "why bother" syndrome. Only a super nice one would make the cut. Writing of Miatas reminds me of a car that won't be collectible... the Ford Capri. What were they smoking? "Huh, we take a Miata platform and put, huh...a really ugly body on it and then we can go home."
I certainly agree that the electronics and complexity of modern cars is going to be a problem. Maybe a younger person should look at buying up computers and other parts such as special edition trim pieces to sell later at unobtanium prices. LOL.
Much of what we are talking about goes back what you wanted as a young person that you couldn't afford then but can now. God my first junky TR3 set me on my current course of wanting, acquiring, building my own good TR3. It gets the blood and can't be cured.
All the Best,
Joel