As the title says, what if Sino-British Negotiations failed and China decided to invade Hong Kong, creating a similar scenario to the Falklands Crisis.
Based on what I have read on this very forum, the UK was never planning to dishonour its treaty obligations to hand back the colony, they were just threatening to withhold extra, non-treaty lands that the Chinese also wanted, if China didn't give into their demands.
If that's true, and China was guaranteed to get HK back anayway, it seems to me they'd be taking a pretty big risk for relatively paltry payback, were they to invade Hong Kong.
(Someone more knowledgable than I am about the treaty and the negotiations can augment or correct my recolletion here.)