Much of the US skyscraper, dam, and bridge-scape is built out, whereas China may be catching up in regions of development. Additionally, China seems to have some level of infrastructure vanity. Dams are falling out of favor here, giving way to "micro-dams", and surely we have much greater environmental oversight (for better or worse). All that said, I believe the US could be more ambitious in the areas of transportation tunnels and high speed rail. There are also many roads that could use wider shoulders for safety/pedestrian/bike use (subtle to some, but actually a really big deal). Future infrastructure may head towards green utopias, transit/freight/utilities underground, above-ground energy producing, ag and pedestrian friendly.