I think it is impossible to predict as it isn't really based on anything other than perceived value, and there is no way to predict what perceived value will be. So just rarity and whatever was flavour of the month, as people have said people spend a fortune on 70s fenders, when in the 80s the standard wisdom was you didn't touch one with a bargepole as they were terrible.
I have played a JV strat and it was ok, not really any better than any current strat, but that isn't really important.
In a world where people pay actual money for a Kay without the intention of burning it to keep warm, there is absolutely no logic to these prices so no way to predict.