Someone on some other site posted this photo some time ago (I've seen it via one of the Pony Thread Simulator videos).
Interesting... it would be sweet if she were Cadance and Shining Armor's daughter, but my guess is that she'll most likely be Cadance little sister. Why am I thinking this? Well, if they were to showcase Cadance and Shining's baby they'd probably have her look like the Cake babies.
The box art shows the character being close to CMC age-wise. If this artwork could be any indication that it's the characters official animation model for Cadance and Shining's daughter, then that would've meant Season 3 takes place far in the future.
However, from what I've seen so far, it appears that the characters hadn't changed that much since the ending of Season 2.
So my guess is, that if it's really going to be one of the characters to make an appearance in the show, it would probably be Cadance's sister, rather than daughter.
Dear Lord, I'm overanalyzing things again...
As for the toy: I personally find it cute. Not sure if I'd want to buy it, as those things can be ridiculously expensive in my country. But once I get my "priority buys" out of the way, then who knows... :>