I watched a video from some Russian guy ( I think it was the same guy who had they had voice a troll in Witcher III) and he mentioned, along with everything we've already heard ( elsewhere), that player would be able to make his own drugs, then put into syringes, etc.
He seemed sincere, but it's surprising no one ( and I watched/read a lot of demo impressions) mentioned this.
Not sure how to feel about this. On one hand, not a fan of unecessary crafting if player can acquire the same in the world: it leads to ton of trash gear placed in illogical locations, has negative effect on economy, and usually you end up with ridiculously OP items that makes discovery/challenge less rewarding.
But if they're planning to, I'm hoping they back to Witcher I design, and refine it, add more complexity to it, than something closer to streamlined version of Witcher III ( that imo, misses the whole point of crafting system).
To those who haven't played, you had different base chemical ingredients with primary and secondary attributes, along with base ( alcohol) that combines them. Primary would define what it does, but if you had more than one ingredient with secondary attribute it would make it more potent or add a different effect, depending on what you combine.
On top of this, CDPR could add here tertiary element to interact with two, that changes how the drugs work, like: catalysts ( increases primary effect, at expense of higher toxicity and/or duration), inhibitors ( reduces primary effect, while rapidly increasing secondary), reverse enzimes ( alters the potency of primary and secondary effects, over time), etc.
Imo, the whole point of (good) crafting system is being able to customize, modify item/potion/spell/etc through variety of combinations form different parameters that can completely change end result.
Good example of this is Tyranny's spell crafting: you take a basic element and define basic function, change it's form, change who it effects, additional elements...number of combinations here can lead to wildly different results.