It's boggling that the US hasn't moved over yet. At a minimal, all Interstate speed limit signs should be required to have both mph and kph (there are a few highway signs like this, but they're rare). Mandate in 8 years, they'll be kph only.
Imperial is only really used in consumer facing situations. If we forced everything over to metric, would it make that much of a difference? Would the US economy suddenly surge due to a more efficient system? Unlikely.
And hey, if it's good enough for NASA, it's good enough for the rest of the states. ;)
Worst hit, would probable be the automobile industry. But I'd say there'd be advantages to metrification there too.
They use metric.