When they said “7 ounces / just under a cup.” that’s not a particular physical cup. A “cup” is an exact measure in the US, it’s 8 fluid ounces, which is 236.5882365 milliliters precisely.
Even if the US does go metric, it will take a lot longer than 50 years for people to not know how big a cup is, all measuring tools in every kitchen are marked for them and the other common units like tablespoons and teaspoons*, and virtually every recipe uses them.
Just in case…
When they said “7 ounces / just under a cup.” that’s not a particular physical cup. A “cup” is an exact measure in the US, it’s 8 fluid ounces, which is 236.5882365 milliliters precisely.
Even if the US does go metric, it will take a lot longer than 50 years for people to not know how big a cup is, all measuring tools in every kitchen are marked for them and the other common units like tablespoons and teaspoons*, and virtually every recipe uses them.
*I wish I was joking.