It's gonna get interesting for the UK, among others, as the U.S. continues to discover that it is broke and can't afford the big umbrella - strategic and conventional - anymore.
Western Europe will either cough up more, or more likely, decide that there's no threat for the next ten years or so. (now where did I read about that in the history books?).
Likewise, Japan and South Korea will no doubt feel a draft as the skirts are shortened in that part of the world as well.