Very realistic. Look, once you have a bachelor's degree you can literally work anywhere you want in the world. So long as you're proficient in English, and you are willing to pick up a second or third language. Many Americans think its a myth and a pipe dream to find full employment in another country other than the US because we are so familiar with our immigration laws we forget that other countries actually look for highly educated and qualified individuals to contribute to their economy. Anyway with that being said. Getting a work/culture/education visa is not going to be difficult with a PHD also you are open to a lot of different occupations abroad. Anyway get your foot in the door with that first job. Also check out Fullbright. Yes, it is competitive. So what? The worse you can do is no apply because well you make it easier for someone else to get it because they chose to give it a go. XD
Anyway I have a professor who just took a job in Macau and he's very excited about the new opportunity before him. Anyway I hope to have an international oriented career. I'm not going to sit here and let some yank tell me that its unrealistic because they haven't done it, and don't know how to do it.
Tip: Someone who discourages you from this goal you must question their life experiences, you must question if they have ever left the US before, you must also question if they have ever been offer a job overseas or a chance to study overseas. If they have none of those experiences then don't take them seriously. Anyone who has had those experiences know that what you are proposing is very much plausible.