Disney has no need to rename "Rapunzel" because "Rapunzel" is really not too gender specific of a name. Naming "The Frog Prince" or "The Frog King" "The Princess and the Frog" however may have presented a small problem to the boy audience because it directly states "Princess" rather than referring to her name ("Cinderella", "Mulan") or her type ("The Little Mermaid", "Sleeping Beauty"). This was, however, a minor mistake... "The Princess Bride", to take one example, was hugely successful with both boys and girls because of its content. I think the real issue lies in marketing. Rather than focusing solely on Tiana, Disney should have also included more of Prince Naveen and his persona in the trailers. The same holds true for "Rapunzel"/"Tangled". If they want it to draw a large audience, they need to focus on marketing to both girls and boys in the trailers. "Tangled" most likely will do much worse at the box office because it isn't referential or recognizable.The problem's not the character types, as the article argues, because all of the Disney classics are hugely successful despite patriarchal, traditional gender roles. The problem is marketing.
I'm not a young boy, so I can't speak for what they like to watch, but I don't think the name of the movie has as big of an impact on the audience it draws as the content of the movie does. It sounds like this movie is going to focus more on the prince than the princess, which, while it deviates from the traditional story, doesn't seem like a bad idea. The Rapunzel story is a typical Princess in distress gets saved by the handsome, but completely void of personality, prince. By giving the prince a bigger role and delving deeper into his backstory, the movie will have more substance and appeal to a wider audience.