You're always going to have some old dogs that just won't convert.
Back in the mid-70s I was a design draftsman for a manufacturer of earthmoving machine digging accessories. All of the dimensions on our drawings were shown in both inches and metric. But the shop General Manager refused to even consider metric dimensions.
He also had a fairly poor knowledge of decimal measurements.
He was in the office one day and we asked him, "Robby, how many thousandths are there in one inch?"
He thought for awhile and finally said, "Jeez, they're tiny little things...there must be millions of 'em."
...and the company is still in business today.
