You can also 100% rule out the SR-71, there's no way it would ever make it through the LEGO ban on post 19 century military hardware. The Soyuz is also (unfortunately) fairly unlikely given the current situation with Russia. Personally, I vote for Land Ahoy: It's realtively simple and not too big, but cool looking and (I think) already enough structurally strong to be made in a set. The Rubik's cube is also pretty cool while not being massive and complex as the Solar System model, but its mechanism seems too flimsy to be selected for production (despite all the amazing efforts by the designer to make it strong as possible).
