Based on the NEX’s history as product model, I believe it is just the general product development and release on Sony’s part.
•Initial release was the NEX 3as the base model and the NEX 5 as the upmarket model.
•The NEX C3 was released to supersede the NEX 3. The C3 body had a new shape but majority of its integral functions were the same as the NEX 3. Production of the NEX 3 slows down and eventually ceases and any remaining products sold at heavily discounted prices. The NEX 5 remains the as the upmarket model.
•The NEX 5N was released to supersede the NEX 5. The 5N had the optional EVF accessory, a touch screen, slightly modified sensor and UI, Production of the NEX 5 slows down and eventually ceases with any remaining products sold at a heavily discounted prices. The NEX 7 was announced to be the line up’s professional model but release was severely delayed due to the floods in Thailand.
•The Sony F3 was released, It’s the first NEX to have a 180 degree flipping screen, and a modified UI that incorporates Sony’s auto frame correcting mode, it’s also the first model other than the NEX 7 to have a pop up flash (no more of that small accessory flash accessory). I’m not sure of the following; touch screen?, accessory port to be able to use the EVF accessory? Modified sensor?
Just by the NEX’s timeline, I really won’t be too surprised if the NEX F3 ends up superseding the NEX C3, after all “why get the C3 when you can get the F3?” which was what happened to the NEX3 and the NEX5.