As an aside to an aside: The metric system has not been very successful in Canada. I was discussing the metric system with a young fellow (22 years old). I asked him how tall he is and he hesitated before replying, "Six feet."
I live in Australia, which has been metric for years. I grew up only ever being taught the metric system in any official sense. However, my parents grew up in the pre-metric era, so I guess I picked up some old measures from them.
If somebody asks me how tall I am, I usually give my height in feet and inches, and that's still quite common in Australia. If you ask me how tall I am in centimetres (something that is quite common on medical forms you have to fill out and the like), then I struggle to remember and sometimes even have to convert. On the other hand, I have no real feeling for how long a mile is, whereas a kilometre is more of less instinctive. I
know the conversion, and can make it if I have to, but there's seldom a need. I
think in kilometres when it comes to driving or flying distances. All the road signs in Australia give distances in kilometres and speeds limits are in kilometres per hour.
I have no real idea how much is in a pint of fluid, but I have a good idea of what a litre looks like. Milk comes in 1, 2 or 3 litre containers where I live. Petrol is sold in litres and the cost is in cents per litre. Actually, come to think of it, I do have some idea what a pint is, but only because some pubs serve beer in pint glasses. (And, on third thoughts, I vaguely remember there are different definitions of a "pint" - or is that wrong?)
All our weather reports give temperatures only in Celcius degrees, never Farenheit. I still have to do a mental calculation when an American tells me it is 70 degrees, and I only really bothered to learn how to convert F to C quickly when I went to the US. I needed to know so I could make the temperatures there make some sense to me.
I guess what I'd say about Australia is that for all serious stuff things are metric these days. If you buy a screw or a plank of wood, its size will be metric. But there are echos and cultural memories of the old measures that persist. People will still call a certain size of a plank of wood a "four by two", which is inches, even though it may not be quite that size and will have a determined metric measurement. Similar kinds of things exist in different spheres of life - like the pints in some pubs. But the old measures are much more "niche" than generally applicable.