You're right, of course, but I think we all get a bit confused about titles at times. They're a bit of a minefield except to those who really know their stuff inside out - as you seem to do! And in any case, Kate will always be Kate to most people, that's the downside of having gone out with William for almost a decade before their marriage. We've known her so long as Kate Middleton that even the newspapers still call her by her maiden name at times. And before anyone bounces in about 'disrespect', it's nothing of the kind, it's just what everyone seems to call her in ordinary conversation. I've never heard anyone say 'I loved the Duchess of Cambridge's dress, that green one'; they'd say 'I loved Kate Middleton's dress, ...'.
Sorry, think I got side-tracked with my own thoughts there! I'm sure someone will be along to sort out the forum title soon.