"Frozen" has officially become Disney's biggest hit, crossing the $1 billion mark. If it were any other studio, the sequel would have its release date booked already.

But Disney is not any other studio. They have set high standards and even with their biggest hits like "Lion King" the sequel was only released directly to video. Not to mention the influence of John Lasseter, the former head honcho at Pixar who is now Disney's creative director. He always maintained that a sequel should only be done if there was something new and something better to offer.

That sets a tough task for "Frozen." Aside from the huge box-office rake, the movie based on "The Snow Queen" by Hans Christian Andersen was a toast of the critics. Hailed as Disney's best in over two decades, the bar is set high, to say the least.

Fans of the Snow Queen would be delighted to hear that they will see Elsa in another form, in another medium. TV show "Once Upon A Time" will feature Elsa in Season Four. It was confirmed by The Hollywood Reporter who interviewed the series' producers, Eddy Kitsis and Adam Horowitz:

"THR: So you'll base the character on Frozen and not the original fairy tale?

Horowitz: We are dealing with the world of Frozen. We are honored to be allowed to do it. We loved the movie. We fell in love with it when it came out last year like everyone did, and we want to do our best to do it justice.

Eddy Kitsis: [What] we loved so much about the character of Elsa was that she was considered a villain but she never really was. She was misunderstood. That, on our show, speaks to us so strongly, that it was a toy we had to play with. It's funny because I see lots of people [saying] "Oh! Did Disney ask them to do this?" It's quite the opposite. It's actually quite hard to get these characters on the show. It's not like you get a call from Mickey Mouse saying, "I want you to sell mermaids this week." It's the opposite. It's very hard to get these. We were very honored that Disney allowed us to take this toy off the shelf and let us play with it."

The producers also explained that they watched the movie three times and fell in love with it (just like every little girl in the modern world). An important question:

"THR: Will Disney have substantial input in how she's incorporated into the show or will you have free rein?

Horowitz: The process I'm guessing it will be similar to how it's been with all these characters. In many ways, it's like using Snow White, using a character from Frozen -- it's just a hundred-year difference. Our scripts and our ideas get vetted by the studio and the network and Disney's brand management people, and I'm sure that process will continue."

Continuity is important because obviously, Disney is not finished with the "Frozen" characters yet. Elsa has deep issues brought about by her powers and her eventual isolation. Such serious topics would not be the theme for a "Frozen" sequel, and they decided that this was an opportunity to develop the character elsewhere.

The "Frozen" sequel will most likely be about Elsa and how she completely moves on from her issues and exercise her right and duty as a monarch. The love interest? Let's leave that to the writers for now.