First, you assume that people know the imperial system (I know it is easy, and you do) but not everyone knows it. How will you re-educate the entire country?
2nd. If you phase it out completely on new devices you are going to have compatibility issues, and people will have to do conversions and won't know what to do.
I have no problem with puting SI as primary on everything, but I don't think it is wise to remove imperial since that is what people know.