Air Force bites off more than it can chew.

Or fund.  The big three money suckers.  The F35 fighter.  Cost is outta sight.  The software isn't finished.  The gun doesn't fire, the engines cannot take more than 5.6 G.  The KC-46 tanker project.   The Air Force managed to gold plate a simple "put tanks inside a well proven airliner" project into an ongoing boondoggle that is running late and over budget.  The new B-21 strategic bomber, this is going to be a somewhat smaller, and hopefully cheaper, version of the B2 bomber.  It's just getting started, but the project did make it thru a bid challenge by the loser[s]  (Boeing and Lockheed).  Aviation Week did not offer much in the way of cost estimates on the big three.  I'd guess $1 trillion over the next 10 years. 

And, after the top three projects, we have a four projects  in to the Request for Proposal, going out for bids, study project phase.  We have a new jet trainer to replace the capable but ageing T-38 Talon. A new ICBM to replace the Minuteman III.  The Long Range Standoff Missile to arm the new B21, and re arm the B-52, B1, B2 fleet.  A new helicopter for VIP transport. 

And even further out, an A10 replacement.  Which is hard to think about.  The existing A-10 is good at what it does.  It's a ground attack fighter that can fly low enough and slow enough for the pilot to see and hit his ground target.  Once the airplane can do that, it isn't fast enough to dogfight with mach 2 jet fighters.  The answer to this short coming is to provide fighter cover for the A-10s as needed.  Bombers have needed fighter escort ever since WWII.  

   The Air Force isn't going to be able to round up the funding to do all of this stuff at once. 

Legacy Weapons Systems

The Economist, at the end of a piece commenting upon Ashton Carter as new US defense secretary, said this.  "To fund new weapons and technology Mr. Carter will need to axe legacy weapons systems (such as the A10 tankbusting aircraft). "
The A10 is old enough to be bought and paid for.  It works.  Should we desire to push the Russian tanks out of Ukraine, a couple of squadrons of A10's could do the job handily.  Keeping the A10 flying is a bargain compared to the pricey, new, not-paid-for  F35.  The Air Force, run by a fighter pilot mafia, wants to dump the A10, largely because it is no match for a real jet fighter.  They see themselves at the stick of an A10, and helpless against a MIG.  The answer, is to create US air superiority over the battle field, and make sure the A10 squadrons have fighter escort.   To be a good ground attack aircraft, the A10 has to fly low and slow so the pilot can see his targets and get close enough to hit them.  You cannot fly between the trees and under power lines at Mach 2. 
  Plenty of potential US enemies have lots of tanks.  Few of them have jet fighters that compete with ours.

Warthog Fan Club

The Warthog, more formally the A10, is a close support aircraft.  It isn't a supersonic fighter, it's a jet version of the Stuka.  Which is why ground troops love it and the Air Force wants to retire it.  With a 30 millimeter (inch and a quarter) Gatling gun it is tank buster supreme.  What the rotary cannon cannot deal with, bombs and rockets slung under the wings can.  But, with a top speed of less than 500 mph, it's dead meat against enemy fighters.  The Air Force, run by fighter pilots,  wants to fly air to air against enemy fighters.  You don't make ace no matter how many tanks you bust.
   Any how, there is now a Save-the-A10 Facebook page with 2722 likes, and any number of after dinner speakers supporting the old Warthog. 

So how hard does sequester hit DoD?

Hard enough to make the generals flinch, and flinch a lot.  According the Aviation Week, the Pentagon figures Congressional deadlock will persist up to and maybe thru the 2016 election.  They are preparing for current and even lower funding until 2016 and beyond.  So
  The Air Force is talking about retiring 552 older aircraft, about 10% of the fleet.  On the chopping block, A10 close air support tank buster , KC10 tanker  and MC12-W (the Beechcraft King Air fitted out for reconnaissance). 
  The Army will loose 18% of its soldiers. 
  The Marine Corps will loose 7% of its soldiers
  The Navy drops from 295 ships to 255-260 ships.

Reducing the size of the Army and Marines means that in event of war, they have to work harder.  For Iraq and Afghanistan we were able to send the troops on one year combat tours and then rotate them back stateside.  If we run out of troops, then the combat tours get longer, they get extended, and the rotation home goes away.  It's tough on the troops, and tough on their families, but we have done it in the past.  In WWII troops enlisted for the duration, and nobody got rotated home after a one year combat tour.  (except the Air Force got rotated home after 50 missions, if they lived that long)