Short answer: No
Long answer: Shun's redesign is based on early concept design from the original game, in which he was meant to have a more gamer-esque look, until it was decided to make him more of a shota-themed route. That being said, while some of his sprites may receive small adjustments in the future, his design is pretty much set. Do also bear in mind that there are hardly any sprite expressions at the moment, and as the project progresses, there will be more. Also, take into account that his story will be vastly adjusted from his original. With that in mind, we won't be budging when it comes to Shun's new design.
Kouya's redesign has been probably the most polarizing out of them all, and while I can appreciate that many have a certain fondness for him, please try and understand, we actually have reasons for this. I can't reveal them, because that could spoil some elements of his story, which is something I don't intend to do. That said, we do actually already have an alternate outfit for him, which has received great reception from those who have already seen it.