IMO, Larian has repeatedly demonstrated that increasing the difficulty of the game is not a priority for them.
If you want to play a tactically more difficult game, I suggest self-imposing restrictions or mod the game, rather than waiting for Larian to overhaul the game for people that want it to be more challenging.
I agree with this. Larian has now done several attempts to provide harder modes, but it looks like the gamers consider them failures, i.e. not achieving the goal they asked for. So, modding, or a DLC could be a better option. One of the reasons I say this, is that the game is already very big. If an additional difficulty level needs entirely new enemy combat AI's and a new distribution of magical items, I imagine it will increase the scripts enormously. For all the players,not just the few % who eagerly wait for this.
So an optional DLC would be better and could maybe really attack the core of the problem.
Personally, I don't have a problem with combat difficulty, but I would love to see some more roleplaying options and sidequests using diplomacy or treachery, and also an extended character building. But this would similarly bloat the game for everyone, while only a few percent of players would use it or notice the difference. I would be willing and eager to buy an optional DLC for this, if that could make it happen.