Should it be Jack frost to be with Elsa in アナと雪の女王 2???

No.
Personally, I think Elsa should stay single.... But ignoring that, Elsa and Jack are owned によって two different companies. It doesn't matter if a few ファン want these two to be together, there's no way in hell ディズニー (Elsa) and Dreamworks (Jack) are going to work together.

Nah. I don't hate Jelsa または anything (even though I don't ship it), but I feel like putting Jack and Elsa together romantically (or even as friends) in an official film would just be もっと見る of a fanfiction rather then an actual ディズニー または Dreamworks movie (depending on who would produce it).