Governments often dowdle. The US started in the 1970, and for reasons I'll never understand, decided to drop their target date and put the whole thing in limbo. This was after many gasoline filling stations already had metric pumps in use (and subsequently abandoned). I know of several scientists at NRC Canada that were leaders in new technology of time and length measurements. They had a better caesium clock (so did GB) than us Americans. But an American got the Nobel last year for laser cooling of atoms, so one can get emission lines with practically zero doppler broadened line widths, which will lead to abandonment of the caesium clock as the standard. Length is already defined by time. The proportionality constant is the speed of light in a vacuum (299792458 kilometers per second).