Countries are a human construct for the management of people and their interactions. They only exist because of a consensus of their inhabitants and the governments of other countries.
That means any claims to ownership of land only exists because of that same consensus. In the modern context, a country ceases to exist when its land disappears, which is a real possibility for many pacific island nations. When that happens, its people are stateless, unless accepted by other nations.
Countries typically originated around locale-based cultures, but that basis is being challenged by international travel and migration, particularly if forced by conflict or weather. Countries change when the will of its people changes, and that is evolving as peoples' circumstances change, whether it be by conflicts, economics or aspirations.
Governments trying to impractically limit changes in any of these will ultimately fail, despite the presumed infallibility of their leaders. Unfortunately, people suffer at the hands of such despotic regimes until they let go, or their people force a change of government by force.
So-called nations-in-exile are a misnomer, as they are expatriates who have lost control of their country. Whatever structure and residents left behind are the government of the country, for better or worse. Other countries might put pressure on them to change, but, in general, possession underscores the reality of government.
The ephemeral nature of nations, in comparison to the earth, means that when it comes to the crunch, the earth is more important, as it is real. It provides an environment in which we can have our pretence of countries and land ownership. Patriotism for a nation is fine unless it conflicts with the health of the earth. Then that patriotism is just selfishness that undermines our very viability.
It is thus the responsibility of every country and its citizens to ensure that the earth is kept healthy. Due consideration must be taken in any decisions at a national or international level to ensure the earth's health is paramount: more important than any advantages a country may desire from it.