the first polymer pistol was an HK
...
Gee mac, you and your hk's...
Ok I'll have to admit, when I was in high school, I saw a vp70z and I really wanted one.
Now fast forward 40 years. I met a guy who actually owned one and he said the trigger was pretty horrible since it was meant to be more like a submachine gun.
I am glad I did not rush out and get one.
Since the op didn't really define what a FUTURE classic is I just made up my own definition, which is basically a recent trendsetter.
A lot of the afformentioned items are old classic firearms already. Eg. Sw m29 and ak47
A lot of items mentioned are truly unique and valuable, but they did not inspire trends and imitators.
If I loosen up my definition, I could indeed include the hk vp70 as classic since it was the first polymer striker fired pistol.
I could also include the rem nylon 66. I believe that to be the first polymer stocked rifle made.
Another candidate would be an hk91 ...maybe.
Anyhowz, FWIW that's my take on this interesting and thought provoking topic.