I don’t believe the US will keep on downsizing. Such change will happen once Obama and his enablers lose influence or better yet lose any participation relative to the structuring of US armed forces.
I wouldn't be too sure. We have been downsizing for decades. The problem is one that besets great nations and how they handle the welfare state. We are witnessing the old battle between Guns vs Butter. Butter usually wins because it has more constituents.
You just have to look at the decline of the UK. No troops East of Suez became a mantra as the struggle for resources became more and more acute. Nations like the US and the UK start rationalizing the reductions in the military by changing the scenarios. We once had a two and one half war strategy and built our forces to meet those conditions. When I was in the US Navy in the 1960s, we had a 600 ship navy, compared to the less than 300 now. The other services have experienced similar reductions.
You can rationalize these reductions using changing threats, better technology, etc. They have some basis in fact, but they are also driven by the fact that we have defense competing with the voracious welfare state that now consumes almost two thirds of the budget. The entitlement programs are growing and growing as our aging population increases.
By 2030 we will double the number of those over 65 to 80 million. By 2030 there will be only two workers for every retiree compared to 16 to one in 1950. And we are already borrowing about 40% of the money we spend. And once interest rates rise to normal levels, our debt servicing costs will skyrocket on our $18.5 trillion national debt that was $10 trillion when Obama took office and $5 trillion when Bush 43 took office. In sum, our national debt has almost quadrupled since 2000.
The US is on the same path of military decline that the UK followed as well as the rest of Europe. In the case of the UK and Europe, they had the US security umbrella protecting them. We don't have any such luxury.