As we know, not all highlight intros are true/canon to gameplay (e.g. Moira’s tennis intro, Echo’s fans intro, etc.)
So for either McCree or Ashe, I could see an intro where they drift into scene on one of those hover-bikes/hover-choppers like the ones on Route 66.
For Ashe, I’m thinking when she drifts into the scene, she points in the same direction her hover-bike was moving, then BOB crosses in front of the screen but on the opposite direction, and as he exits the scene you can see Ashe facepalming in annoyance.
For McCree, when he drifts into the scene you can see he’s got a lasso, which he then twirls over his head (still sitting on the hover-bike) and throws it at the screen, “catching” the viewer, who falls to the ground (camera-wise). McCree then proceeds to rev the bike and drives pulling on the viewer. Scene ends in a cloud of dust.