levi
Still fresh, damnit!
Maybe, but I would rather look to the things that have changed already. Bags of sugar are now stated as being 450g which is slightly smaller than a traditional imperial pound, but close enough, although more recently they seem to have become 500g due to larger bags simplifying to 1kg (rather than 900g) and even bigger ones becoming 2kg (rather than 1.8kg). Beer bottles used to be pint sized (some 568ml to the nearest ml), but are far more commonly 500ml these days, in the other direction.Regarding the carpenters, I meant there would still be doors available fitting the x-inch-measurements - just for there would be the need for them, or out of tradition.
I suspect the same will happen to doors in time. A 76cm door will fit a 30 inch frame with only an extra 2mm on the gap at the bottom, and presumably a smaller gap at the latch side which is unlikely to cause any problems in latching. Granted, if you were building a frame for an older 30 inch door and you assumed it was 76cm, depending on how close to the standard the door was, it won't fit, but it's a poor carpetenter who makes a door frame without measuring the door first.
Maybe windows would be a better example, but as far as I've found those are generally specifically cut to size by the glazer, because the holes in building can and are in practice almost any size and shape.