2F/2F,
In absolute terms, your selections are hard to argue with. I initially thought of the same definition and examples that you did.
However, I think "classic" has come to encompass a broader meaning. Otherwise classic car shows would be rather boring. The '57 Chevy Bel Air would be allowed but not the sedan. Which is the classic Avanti, the Studebaker or the later ones? And anyone knows the Jaguar XK 120 is the pattern for the 140's and 150's, though all three are considered classics.
I think "classic" can be that which initially defined a class, and also a member of that class which expresses well the qualities of that class. The class can define not just a type, but a time; for example, "a classic mid-60's Japanese 35mm rangefinder".
The Nikon F3, the Pentax LX and the Canon F-1N all define what the pro level interchangeable prism camera was in the early 80's. To me they're all classics as they all represent a different design approach to the same class of camera. The Nikon F2 was THE pro camera of the mid to late 70's, in that time the classic photojournalist's SLR, and the one desired by the most people. The Canon F-1 had a considerable following and to me is every bit as much a classic. That's because it's a wonderful example of Japanese design and engineering of a certain time, was aimed at the pro market, but was certainly not a copycat of the Nikon F series.
To me, the OM-1 is a classic because it defined a new class and a new design philosophy, the very compact SLR.
One reason it's classic, like other classics, is that it was so well done. Its big bright viewfinder and lower noise and vibration were very influential, and defined an approach that was about more than compact size.
I think it remains, with its siblings, in a class by itself as a compact system SLR, by virtue of its very extensive system. The Pentax MX for example, is a great machine, but its system of accessories, while enough for most people, did not match up to the Olympus system in scope.
The MX and the OM-1 are both classic examples of 70's metal bodied, all-manual, very compact SLR's; broadening the class to encompass all compact SLR's, machines like the Nikon FM series exemplify cameras which were for many, "just right": not too big, not too small.
I know the notion of "classic" could be parsed down to the point of absurdity. I just think "classic" can be defined more strictly or less strictly without losing meaning.