North Korea united with South Korea
Kosovo united with Albania
Cyprus split up, Turkish side becoming Turkish, Greek side becoming Greek
Vatican City becomes part of Italy
These European countries or city-states could be absorbed into the larger country that surrounds them
Vatican City
Liechtenstein
Malta
Monaco
Malta doesn't make much sense, the only country they could merge with would be Italy, and with the exception of their religion they have very little in common with them, not even speaking the same language.
