Per the QDR, the C-17 Buy Stays at 180:

No more than 180 C-17s figure in the QDR, say senior USAF officials. How that will play against the push by Congress to up the number by 42 is unclear at this time. Air Force officials plan to investigate how they could stretch the production line an extra year or two. Boeing already has approval to market the aircraft to allies, but even at its present, amortized price of around $200 million a copy, the C-17 is a really big-ticket item for even America’s wealthiest allies. Japan and the UK are two possible customers; the UK leases some C-17s already. Air Force officials also would like to see some older, less refined C-17s, go to airline and air freight participants of the Civil Reserve Air Fleet.