Monarchy? Oh I say, we are most amused. If you knew any history of the Enlightenment, it was around that time they were kicking monarchs out, both English and French, then only ever brought them back as constitutional monarchs, if at all.
As for the Austrians, your Archduke Franz Ferdinand heir to the throne was shot, causing WWI, which was all his successor inherited. Emperor Charles or Karl Franz was deposed, he died in 1922, but does have descendants. Imperialism was what ended the Austrian Empire, they are now as archaic as the Roman Caesars were.