One very common justification archaeologists give for their field existing beyond heritage preservation is that it can help inform our own responses to future events. Archaeology/history is our only long-term view of societies and how they've adapted to changing conditions historically.
The actual application of that research remains a bit limited though.
It doesn't necessarily have to have a direct future-looking application; just comprehending why things are the way they are today, has value in itself - particularly in the political sphere.
