Honestly, I would love it if Hasbro released a Blu-Ray version of My Little Pony: a New Generation, as that could be shared with people that don’t have a Netflix subscription (and don’t want to risk going onto a pirating site to watch the film that way). Not only that, but it could be a collectible to market the film, possibly including an art booklet including concept art for the film (and likely some for the TV series as well).  
In regards to your Blu-Ray design, I honestly really love the inside cover, and I think the outside cover makes sense, though I think there are better poster images that could have been used for the back of the box (and knowing what actual DVD boxes look like, chances are a Hasbro-released copy would have a back cover that is covered with screenshots of the film as well as the synopsis for it, and various information about the cast that worked on the film and its runtime). It will be really neat to see what the final Blu Ray looks like, should it get released physically.