Star Wars: The Force Awakens - 10 Moments Everyone Misunderstands
5. Kylo Ren Is Now Irredeemable

Ah, fan theories. Kylo Ren's arc is going to mirror that of Darth Vader, so of course he will be redeemed by the end of the new trilogy, right? Or, even crazier, Kylo Ren is a double agent, and is taking down the First Order from within. He killed Han for that reason - it was all part of the plan. Both of those have genuinely been stated a fair bit since The Force Awakens, and, well, no.
The double agent idea doesn't make any sense, because he quite clearly feels the pull of both the Light and the Dark Side, and he's been made into such a complex villain that him being a double agent would be plain stupid, not to mention no one would ever agree to a plan killing Han.
As for the redemption, it's more understandable (and the novelisation even discusses how the act weakens him, rather than strengthens him as expected), but, frankly, you do not come back once you've killed Han Solo. Ben Solo may have felt that he was being pulled in different directions, but by killing his father, and then fighting Finn and Rey (and now off to receive more training from Snoke), he has ensured that he is not redeemable.
Going down that route would be too derivative of the original trilogy anyway (although they obviously don't have too much of a problem with that), but this is Han Solo he killed, a character people have such a strong connection too. There is possibly a way you attempt to write that redemption arc (and Kylo's redemption is probably a point more up for debate than others), but a lot of Star Wars fans wouldn't buy it.