I think this problem could be alleviated by having a main character stuck in that hallway with Vader. Maybe a current character could be rewritten to be in that scene, or it could be a new character. The idea is that the audience is hopeful because this character managed to avoid the destruction of Scariff, so we’re rooting for him to get out of there.
They could A) make Vader the antagonist or B) use him in place of CGI-Tarkin. The problem then becomes writing him in properly, instead of him randomly meeting nameless guys in a hallway. Imagine if they wrote in a Jedi hunt plot around this which leads them to Jedha and wraps back around to Jyn and friends.