We're already there.
Ask Manuel Noriega, Muammar al-Gaddafi, Saddam Hussein, or Osama bin Laden about how much restraint the US shows in acting directly against foreign leaders. I know that of the four I mentioned, only that last was actually assassinated, but they each, very personally, experienced the joys of being on the shit list of the USA.
Please note: I don't necessarily support any of the above actions, I merely cite them as historical events.
The only thing that has kept the leader of North Korea alive is that he is a pet of the Chinese. No matter how wacky he is, his nation serves as a buffer-state that prevents China from directly sharing a border with South Korea. To be fair, we (China and the US) probably both like it that way.
I think that making a farcical movie about assassinating foreign leaders actually pushes back against the US being acclimated to taking such direct action, because nothing threatens authority more than mockery.
My opinion only, YMMV