Well, to achieve the level of tactical decision making you're talking about, they would need to make (something along the lines of) an Imperial Assault clone for Xcom
Not really. In fact that would be ridiculous and games would take FOREVER. I dont want anything that complex or time consuming added to the game.
I would just like to see players having more choices during combat. Like being able to equip your soldiers with items before they go on a mission or defend the base. They might just be one use items like medkits or grenades but they would help you curb bad luck. Additionally I think each class of soldier should have a unique ability, not just different skill icons. Like supports might be better at using the medkits I mentioned above, etc...
Interceptor combat could be made more interesting by having different types of alien ships with different abilities. And also having at least one more type of interceptor, thats based on UFO tech, and has to be researched.
These are ALL things that can be remedied in an expansion, and I have no doubt they will be, but as of now the game feels incomplete to me.
Khobai this already exists in the game. The entire point/goal of the Research Scientist is to research tech/assets for all four positions. This includes things like alloy cannons, rocket launchers, etc to give to the squad leader.
Every position has more strategic options as more research is completed. How many options they recieve is in and of itself ALSO a strategic choice because the research requires funds.