As I watched the episodes Ash's previous female protagonist cameoed in, I noticed an interesting pattern. After each cameo, the girls get closer to the champions of the previous region. When Misty returned and she left, Lance had then returned for the Team Magma and Team Aqua arc. They were in separate episodes and appeared in different times. When May returned, Wallace returned as well. They didn't interact, but they were in the same episodes they were featured in. Come Dawn's return and Cynthia returns as well. This time, they lived under the same roof. Dawn even interacted with Wallace, and now Iris interacted more with Cynthia.
If this pattern continues to the generation six anime, then Iris and Alder would cameo and return. Now... what connection do they have in the games? In the Memory Link feature, there's a memory where Iris battles Alder, wins, and becomes the Champion of the Unova region. So if we go on with the pattern of how the previous female protagonist and previous Champion of the region Ash previously travelled to get closer, Iris and Alder should have a battle that determines if Iris should be the Champion.
Which means that when Iris comes back and has her inevitable cameo, assuming that she gets replaced, there's an extremely high chance that she'll become the Champion of the Unova region in the anime as well.