> that definition precludes the idea that new types of user interaction can ever be "intuitive" if they do not conform to an existing one, which is, in itself, an absurdity.
The definition I've always liked is: An intuitive user interface is one that works in the way the user expects it to.
If the user is already used to an old version of your software, this can be achieved by making it work in the same way as that - but that's not the only way. As long as it works as you expect it to, whether that's due to user memory, or well-thought-out visual metaphors, or analogy with another piece of software the user has used, or just good design, the definition is satisfied. If the new software works in a way that violates the user's expectations, and reacts in ways the user doesn't expect, it fails it.