I started playing Disney Heroes Battle Mode last October, not just because of Elsa was added in the game that time, but also I am 100% fan of Disney, since I was little. After the update 1.15 in last November, Elsa’s outfit has changed into her Frozen 2 travel outfit permanently. I really missed her iconic snow queen dress so much, that I gave my suggestions and ideas to the game forum. I know that time was advertising Frozen 2, but it wasn’t a good idea for having Elsa’s travel outfit in the game forever. Although her outfit was changed, but her appearance in the loading screen and friendships with other characters are still in her iconic snow queen dress. I hope the game can bring balance the elements of both Frozen 1 and Frozen 2 to Elsa in the game, so that some players(who haven’t watched either Frozen or Frozen 2 yet) and new players can learn the character’s story from a small bio and different names from each skill (To clarify that, Elsa’s skills are based on Frozen in the beginning, while her travel outfit look are based on Frozen 2 after the update recently.). Also, since Elsa’s iconic snow queen dress was introduced in the beginning before update 1.15, I have an idea of providing Elsa a costume section, so that we can switch Elsa’s outfits(We don’t have to collect threads, if Elsa’s travel outfit was changed after the update). 
Short answer, No.
Longer answer, It was probably Disney that wanted her image to change with F2 and when PB updated her skills I’m sure they update her model too (and not just her skin). From a personal view I like her appearance far better with Frozen 2 look.
I would have liked to have the costume, but unfortunately PB has no plans for costumes anymore. And as Emitz mentioned, they changed her animation a bit (I think her defeat animation is inaccurate now 
which is why I also get the impression Disney had some hand in it).
Otherwise I think the new outfit is more practical for battle 
I’ve been trying to get PB to change it for a while and they have not gotten back to me about it!
Keep trying. Or mention this in the next Q&A.
I did mention it in the most recent QandA but still no response
Yep.defonately.talking about frozen II,kristoff & sven are coming soon