The various overtaking traffic scenarios are not unique to pacelining nor drafting. Our club had a fatality last year when a rider stood on a climb and swerved or wobbled just a bit while in a traffic lane and about to be overtaken by a too close logging truck. The truck clipped her bars, causing her to fall toward the truck and go into/under it's trailer.

I only mention this, because I believe overtaking traffic to be a significant risk, regardless of whether one is pacelining/drafting or not.

On a couple of occassioins we have assumed a double line in order to place less experienced riders against the cub, protect them from the overtaking traffic, and better occupy the lane with experienced riders who are more capable of absorbing the air blasts from passing traffic while encouraging that traffic to only pass if they can do so while moving almost completely into the next lane.

Like driving on the highway or any other activity at high speed and around others, situational awareness is paramount.