Things in the Army aren't really slowing down. More combat hardened units are now finding themselves deployed on rotations in support of Theater Security Cooperation Programs doing training exercises with foreign countries. Dollars are dwindling, unit fill rates are going down which all translate to more work with less resources for those that remain. It becomes a real leadership challenge to balance it all so your Soldiers can still execute their mission.
Competition when it comes to retention also comes into play. In addition to slowing promotion rates for junior officers, there are separation boards at the Captain and Major ranks as the Army seeks to drawdown. As tug says, those that put it on cruise control will be left, and possibly forced, out.
What does this all mean to someone considering WP? I'd take it with a grain of salt. A lot can happen between now and the 4.5 years until 2018 graduates, and even more until y'all reach the end of your active duty service obligation. If you talked to the candidates in the mid-90s, the Army they saw was coming through another drawdown, and the heavy action was Kosovo and Somalia. They became the LTs/CPTs that were at the front of the post 9/11 conflicts, benefitted from elevated promotion rates and are now moving to become the Battalion Commanders (and by your graduation, Brigade Commanders).