Why think about 50 years down the road, plastic or metal aside, the design is so much better today than 30 years ago. I think I laid it out in detail in post #12 already. Like someone said the old gun designed by J Browning 100 years ago and was popular for a long time, that it set the standard of semi auto pistol. He was a generous, he created the original design, BUT people improved his design and make it better and better. Like Bruce Lee changed the whole martial arts scene, made a quantum leap in the 70s in fighting. But people learn and improved upon it. I don't think Bruce Lee would last 5 minutes in the Octagon of UFC today. That doesn't mitigate his achievement and contribution. What is the best today might not be worth looking back in even 20 years.
Von Braun invented the rocket and designed the Apollo that went to the moon, but you serious think it can compare to the new rockets today? People moved on.
I won't worry about whether Glock would still worth keeping in 20 years. All it matter is the new guns are much improved in terms of reliability than the old ones. I have enough old ones to say this. I got the best at the time, none are that reliable without a lot of work I had to do myself. What make you think guns still use gun powder in 20 years? They might come out guns using lazar or something else!!!
I never knock on steel frame guns, only the aluminum alloy ones. I said steel frame is the best, just the weight.