Geology - Although much greater than one would expect from games, the Dwarf Fortress (solid rock) underground is still bland compared to real-life underground. I want to know what things Toady is planning to do with it. And, how he will integrate it with the new releases (cave) underground? Aside from the obvious multi-level distortions in rock layer and ore, I also want to know about large crystals forming. The kind of crystals that can fill an entire room and would take up 6-10 spaces in-game (distributed horizontally, vertically, or diagonally [when viewed from the side]).
Physics - This one could easily shift to something else, but I was intrigued by learning when Toady might add code for floating objects (seabirds, flotsam, bottles, and oil). And how he might solve or switch the current quirks of liquid movement. Arcing airborn objects is low on my list within a list.
Linguistics - How far will Toady go with procedural language and speech? Even if it's fleshed out some, will it continue to be the "{Greeting}, I am {name} a/the {profession}"? Or will there be procedural sentence structures with a system to skew conversation based on all circumstances the character knows of (going beyond the "are you in a fight?", "are you on your way home?" and "is the player an enemy?"). Getting a generator working for such things would really flesh out adventure mode, even if it would only be a bonus for fortress mode. If such a generator was made at masterpiece quality it would allow the kobald language to function as intended; what first appears to be gibberish makes sense when you know some of where it comes from. I think the poetry maker would be a good start; you could add it right beside traveling theater troupes.
I find it odd people pick Astronomy, consider most of what they want from it is tied to the magic arc, and that's for some time to come. The rest of what people want from it will have little and vague effect on the game.
I think the sciences refers to how each science will be applied, not by the dwarves on their world, but by Toady on the game.