There is a handy library I used, draft-js-export-html. Import the library and you should be able to see HTML once you invoke the function, stateToHTML:
console.log(stateToHTML(this.state.editorState.getCurrentContent()));
I’m pretty new to React so hopefully this works for you. I looked under the hood of contentState and there is a fair bit going on there that makes using a library to parse out the entities that much more enticing.
The author, sstur, answers a tangentially-related question where I learned about his libraries.