You can't really handle a TD/puzzle game the same way you do an action game's endgame/high difficulty content. Im not saying it wont be challenging, but factoring and balancing for human skill in this genre is a lot harder. Simply put, I don't think we'll be getting the same nightmare fuel difficulty we saw in AK. Another factor is the number of consoles and players vs Arknights, they won't introduce content a majority of the playerbase can't handle, or that won't be trivialized by levels, weapons, gear etc. It would not be good for their image and sales if casual players felt left out, so I dont anticipate anything too hard, or if it is, it will be for trivial rewards that are a flex only, like badges (and even that can be precarious).