I would think the Mk1 focus is more akin to something like the Beetle. A classic, in the sense that it brought something to the masses in a way that wasn't done before. You'll see a lot of them all over the world in their original shape, but you will see an equal amount, if not more, beaten up, broken down, not taken care of, etc.
People will respect it for what it is/was, but not value it, if you know what I mean.
There are loads of cars that were cheap and popular when they were being built, but that nobody thought to preserve and look after theirs other than a few old men and hence the survivors are now classic and collectible. Mk1 Mini, Mk1 Ford Cortina, Ford Zephyr, you know like that. I'd say the Mk1 Focus is a good candidate.
In terms of mental cars, that didn't quite fire the public imagination (like DeLorean) what about the Gibbs Aquada that I posted in the 'I need a truck for when it floods' thread?
They will be rare as fuck in a few years. Collected by amphibious car nerds and rich cocks with some water on their land too. Though maybe buying one new might not be the wisest idea.