There appears to be a "Block II" CH-47 in development that features swept-tip rotor blades, uprated engine and transmission, better avionics, etc. In fact, the first few EMD examples seem to be currently in final assembly at Boeing. The Block II program looks to be on budgetary thin ice, though. US Army wants to reprogram money for it's future rotorcraft programs. Given the Army's recent history in big-ticket items, I wouldn't hold my breath.