As a US citizen who is a metric fan and loves using it, in what way? The government did switch - in the 70s - according to its own statutes, it had to.
It has crept up in various places (and I find it hilarious) innoculously, like in 2 liters of soda, or in how computer processors are talked about in mm² die areas.
But the average American still uses imperial units religiously, anywhere they approach a problem involving any unit of measurement they always default to imperial, and having a 14 year old brother I see no change in his education or habits to indicate a slow transition of mindshare. The government moved decades ago, but the people aren't moving at all.
I get the impression it is much like high school language classes - you learn it once early on, never practice it, and by the time you are a full adult you have completely forgotten it. I'm not sure how to improve the situation to actually get the people to start using international standards, because if you were to start trying to force it on the supply side people would just not buy metric tools and information because they forgot it back in primary school.
1. Make sure everyone is educated in metric
2. Change the easy things: the paper size the government uses, the units on food labels, the measures legal to use for sales of loose food or other goods, the units the government uses for all types of reporting. (Therefore if businesses want government contracts, they'll need to use metric.)
3. Change other standards, like residential construction, preferred fasteners, wire sizes. Where old measures are required for compatibility, write "24.5mm" in the standard. If the dimension could be changed to 25mm without any side effect, use that.
4. Change other things people see daily: I don't know if doctors use metric in the US, but I assume they communicate to patients in old units. Change the default, but accomodate older people. Change the road signs. Is anything left?
The UK is part way through 4, but has been stuck there for decades.