Quote:
...At least during the Cold War there was a purpose - a "struggle" which partially guided us.
That's the quibble point. I agree that there was a purpose (to remain atop the heap) but the belief that we had a coherent plan and policy throughout the 1947-1999 period is way wrong...
I don't see any disagreement there. He didn't say anything about a coherent plan or policy, he spoke of a struggle providing partial guidance. "Partial guidance" and "purpose" are not so far apart.

Of course our system does not lend itself to long term policy. That's both strength and weakness: we veer about a bit, but we can also adapt or discard policies that are unsuccessful or no longer appropriate.

I would say that the "sole superpower" ambition needs to be adapted or discarded; it's neither desirable nor possible. An attempt to maintain sole military dominance without sole economic dominance - which we have not got and will probably never again have - is only going to end with us nailing ourselves to a fiscal crucifix. The challenge is not the maintenance of sole superpower status, but the development of a realistic strategy for advancing and protecting our long-term interests in a multipolar world.