Newer, tier 4 equipment is more expensive to manufacture, which could reduce the overall demand. However, it is very likely that restrictions will be implemented that require this rating on equipment concerning government related contracts
Tier 4 engines will need to be de-tiered to be usable in most markets outside the U.S.—the U.S. is currently the number 1 provider for the global market on used equipment
Diesel equipment is known for its durability, so Tier 4 equipment will represent only a fraction of in-use equipment for some time—which may result in further changes to state or federal regulations, with unknown impacts
As it stands right now, Tier 4 will impact values nationally and internationally; to what degree is unknown.