I doubt it will happen since Houlihan and Purrier are probably going to gap the field by the homestretch but consider this situation.
What if we have an ending like we had in the 2016 Trials 800 meters, where a fall cost Martinez any chance she had of making the team? What if this fall is caused by Houlihan? Whether or not Houlihan gets DQed doesn't matter; someone else's Olympic dreams are trashed because someone who should not have been in the race caused her to stumble or fall. What if Runner #3 is one of her teammates, Elise Cranny or Sinclaire Johnson? If Houlihan thinks the situation is bad now, how will she feel going the practice the next day?
In the Butch Reynolds case from 1992, this could not happen because the race was run in lanes. But the 1500 is different since contact is possible. Look at how many falls we had just last week in the NCAA races.
Bottom line: Houlihan should not be in the race and I hope (although it will not happen) that all other competitors refuse to take the track until she is removed from the race. USATF, do the right thing!