It is generally believed by a large segment of the audience and the majority opinion that Kylo Ren should not be redeemed due to the severity of his actions and the belief that it will be a rehash of Vader. Your challenge, if you choose to accept it is to have much of the audience actually favor the idea of Kylo Ren getting redeemed. I am not saying that he will not be redeemed and I admit I am among the 1% that wants him to be redeemed, but there are lot of signs pointing to the other direction and audience(through backstory could always change things if done well).
Bonus points
if he
still manages to kill Han Solo(this part is spoiler filtered for good reason) but audiences still are willing to give him a chance. The justification is that the horrible thing he does solidifies him as a villain, but not a irredeemable one and while it means he is a villain now, it doesn't mean he can't change course.
Here are some ways which I feel people could accept a hypothetical redemption drawn from pop culture and Star Wars related PoDs:
-Have Episode VII be more original, that way if they want to redeem Kylo Ren it would not be seen as too much of a rehash of the originals and it would actually be expected that he dosen't get redeemed if Episode VII was more original.
-Have GRRM complete ASOIAF early rather than what we have now, Theon and Jamie get redeemed, the arcs are well-received, and this sets a precedence that people believe should be followed
-Have Kylo Ren be less emo, for every person that said Ren is what Prequel Anakin should have been there are those that feel that Ren being emo was a bad idea.
-Reveal that Kylo Ren never truly knew about his father or was taken away from a young age from his parents due to Snoke's influence. This would make the situation more tragic as he would be hard-wired by the First Order to see his father as only an enemy and give him some more sympathy
-OUAT either never comes out or dosen't screw up after the third season(never watched but I heard it got a lot of criticism for its redemption arcs)
-Have Snoke be established in the film as either an Canon and genderbent expy of
Abeloth, Darth Plagueis that has gotten more powerful than Sidious after surviving his own death at Sidious hands and going into hiding OR the Canon equivalent of
the Sith Emperor or some sort of personification of the Dark Side. Having Snoke be seen as objectively more powerful and evil than Palpatine could allow people to feel that Kylo Ren could hypothetically earn his redemption by "killing a bigger fish". Also if it is revealed that Snoke survives by transfer essence...it might not be a good idea for Kylo Ren to kill Snoke and become emperor since the story could easily conclude with Rey vs. Snoke in Ren's body.
-The irredeemable anti-hero character archetype popularized by characters like Walter White never emerges. Maybe Breaking Bad is a victim of the Writer's Strike(as in gets canned as a result) and a sizable majority of people actually and actively get disgusted at Frank Underwood's actions(as in Ramsay Bolton style disgusted) and this leads to House of Cards getting cancelled
-This is a big hypothetical, but have a story exist where a villain willingly kills his/her parents AND get redeemed at the end AND this redemption is well-received.