Eisenhower's concern, I believe, was that industrial interests (sustaining production rates, keeping the "base" healthy) and military interests (once you lose force structure, whether it's bombers, fighters, carriers or submarines, it's hard to get it back) could converge to protect and sustain capabilities that the nation did not need.
Eisenhower was quite clear what his concern was: "
the economic, political, even spiritual" well being of the nation and the "
very structure of our society" and "
our liberties or democratic processes." He did not address those interests converging "to protect and sustain capabilities that the nation did not need."