at the same time прощаться, попрощаться is used often and doesnt' have this 'parting forever' connotation.

Eg, Мы попрощались с гостями и стали мыть посуду - We said good bye to our guests and started to do the dishes. (just an every day situation).

But прощай, прощайте as form of address imply that we are not likely to meet again.