This is quite similar situation indeed. It was once easier to adopt the metric system when the infrastructure was not yet as developed around the previous ones.

Austria-Hungary adopted the metric system in the 1870s. Back then: no cars, no highways, no speeding laws etc. Oxen-drawn wagons in the countryside were not built to a precise spec.

Only the railway, the architects and the artillery had to really switch. Ordinary people would still ask the grocer for half a pound of ham in the 1930s.

USA in the 1970s would have to remeasure all the land communications etc., or end up with a weird hybrid like the UK.

WHat we have in IPv4 and IPv6 is the weird UK-like hybrid...