So you are telling me NATO is a "temporary cooperation based on common interest"? What's temporary about it?
Different subject have different perspective. A child plan in a very short perspective, adult person longer (depends also from intellectual quality of individual). Also human life is usually much shorter than standard existence of the state. Thus term temporary
might mean much longer period of time if we talking about the state.
After collapse of the Soviet Union NATO redefined its principles. When there is no common enemy, such general concepts are less lasting. Your countryman Cyrill Parkinson wrote that political bodies are less and less important when more an more people is offered a membership/voting right. So enlargement is also test for NATO. It is very likely that the strongest members create some smaller bodies which hitjack most of competences of political structures of NATO .