Stephan or Bianca is probably going to be the eliminated rival if there is one. The can't get rid Kotetsu or Virgil because they are too new and Trip had a huge tournament meant to glorify him. However it is possible that are going to eliminate Trip. Now I'm sure plenty of you have heard of this graph. You'll have to click on it I expected it to be bigger
Using the first star wars movie this graph represents ideal the ideal tension curve a hook followed by peaks and valleys. The relevant part is the hook. I think a Virgil or Kotetsu v Trip fight would be a good hook given Trip's recent Junior Cup win and the fact that Trip regained respect for Alder meaning rival wise he's pretty done. All he needs for his story to be done is to gain respect for Ash and that could be done through Ash beating his vanquisher.