I agree with that theory. Plus it might also be a sign of globalisation as in almost every other language the currency is written after the amount
Now the conversion to Celsius and the metric system, but that should probably take another hundred years.
Well here in the UK we still normally put the £ sign before the amount i.e. £50.
I'm sure the states will get around coverting to metric, you've just got to spend a decade or two dual labelling, a few years teaching bofe in school and towards the end only teach metric in school. You set a deadline i.e. by 2040 we will be using the metric system and stick to it. Yes some people won't like esp. if they grew up using the imperial system, but the change is not about the current generation(s) but the next generation and the one after that, and the one after that and so on.
Though which ever system a person uses when writing it down they should specifiy which system. i.e 40C.