Hong Kong situation is similar to Northern Ireland in 80's. She will get a referendum for independence. For how long to seceede we don't know.
Ireland was part of the UK. In 1922, the south became Ireland (Irish Republic) while the north became known as Northern Ireland. It was therefore, and remains today, a part of the UK.
The 1980s to which you refer concerns attempts to get Northern Ireland to rejoin Ireland.
The Hong Kong of today is quite different from Ireland's 1980s situation as the citizens are seeking freedom or, ideally, independence from China.