Not much, as the majority who serve only intend on serving a single 4 or 6 year term. Most people who join have absolutely no interest in going career. They want to get some training, college money, or just to travel and see things they never had before. And some still serve simply because it was a "Family Tradition". I knew one back in the 1980's from New York that every male in the family had served in the Marines since the nation was founded. And just like all of them, he did his 4 years and went home to the farm. I knew two others in the 2000's that also came from such a tradition, but were from rich families. And both pretty much admitted that if they wanted a place in their family companies, they had to serve at least 4 years in the military. Very few serve more than 8 years, and I know a hell of a lot that did 8 or even 10 years, then simply walked away. The "up and out" may be a reason why less stay in, but it is not even on the mind of those that join in the first place. Hell, I bet if you asked 100 new recruits before they go to Boot Camp, less than 10% have even heard of "up or out", and what it even means. Plus, that is only really an issue during the times that the military is contracting. The two big ones I remember were the Clinton and Obama contractions. During the Reagan and Bush Administrations (both of them), one could stay in the military pretty much as long as they wanted because it was growing. But after 1993 and 2009, the military shrank rapidly, and is still shrinking. Going on 14 years, we are probably in the longest running contraction of the military since the end of the Civil War. And with no end in sight for at least another 3 years, even more are going to get pushed out as there are simply no places for them to move up into. Ultimately that may keep some out who had planned on the military for a career, but it will make no difference for the majority that just want to do their 4 years and go home.