I can provide my thoughts. To me, the bags look dated and are dated. The gold of the bags back then are VERY deep yellow, 24kt gold. The stitching/puff is not the same as it is today. It was flatter back then with no "puff" that everyone wants today. The 80s was the decade of flash and deep yellow gold (think Dynasty), so everyone wanted a flashy gold-chained Chanel. The 90s was the decade of minimalism (think Calvin Klein simple lines), and no one who was fashionable would be caught dead with a "gold chain" bag. I wore no Chanel during the 90s... it was out and only stuffy and non-fashionable people wore the flap bag along with their blue eyeshadow.
So... to me, Chanel bags do not last forever. They general "style": (e.g. flap) lasts forever, but the actual bag itself changes. The gold is now lighter, to better suit today's fashions, the quilts are now puffier (very obvious you can see an old bag from a new bag). Even the "classic" flap is now a double-flap. And the CC clasp has also changed. The bag is definitely not the same, and I think true fashionistas could spot a current flap from an older flap (or mini or other classic).
I don't own any of my old Chanel bags anymore for the reasons above. To me, they just felt dated and what is the point of wearing a bag that you feel dated wearing. In my opinion, part of being fashionable is being current, even if it's a refreshed version of the same style. Vintage to me is just old. I prefer to get the newer version of the same "style".
A "classic" to me is a reference to a certain style or shape, like the classic flap. But owning a 20-30 year old bag is old to me, not classic.
Just my two cents. I am sure many foiks love old used bags and plan to use them forever. I used to think that too, and it is a romantic thought and a good marketing gimmick that has been stuffed in our heads. The reality is, I don't wear anything over 10-15 years old... bags, shoes, clothes, etc... it's not that I want to throw things away just to buy new, but the style no longer feels fresh to me. I wonder how many ladies wear things that they have owned for 10-20 years (not purchased vintage because that may be the trend today), but truly wear something they bought 20 years ago. I would think for the truly fashionable... it is rare.
Anyway, my two cents for something to think about. Hope this was helpful.