An interesting thought.
My assumption is that Mr. Braun is still part of the Rounders. The on of the main difference in the Steins;Gate world line is that, since the first D-mail was never sent (well, it was, but it was erased), SERN has no need to come after the lab members. Therefore, Mr. Braun, through the other Rounders, doesn't need to do any killing.
Now, if I'm wrong and Mr. Braun isn't a Rounder anymore, I can't think of a reason why the lab would still be connected to SERN. Of course, the movie might expand the story a bit, so, we will see what happens.
Just my thoughts.