Construction robotics: questions for 2019

There is still so much I don't know about construction robotics. As a field, it is still relatively new and there are not yet many case study. There is still so much I would like to learn and understand. Down here I have listed 9 questions which are itching me the most. The answers are not easy, some of them are big enough for a dissertation. I hope to have them answered at one point in the future.

1. Construction robotics encompasses a big field of different robot types: from drones, 3D concrete/steel printers, bricklaying bots, formwork bots, all the way to exoskeletons. How do you group these different robot types into subdivisions?
2. Each new technology follows a general development cycle: from research and development, to early adoption to later mass adoption. Where is the construction robotics in this cycle right now?
3. I see the problem of "eyes" (environment perception) as one of the biggest problems construction robotics is facing right now. Robots function well in predictable, non changing environments. The construction site is nothing but a constant change, which means that robots have to "see well", understand their environment, and also be able to orientate themselves in the space. How big of a problem is this and how to solve it?
4. What are the biggest restrictions, problems and challenges in 3D printing?
5. Why do construction companies seem so reluctant to use 3D printing? 
6. Steel reinforced concrete is probably the base for all important constructions. 3D concrete printing cannot print around steel reinforcement. Can this problem be solved? Could some kind of reinforcing fibers be good enough? Could it ever be used for the demands of construction statics? 
7. How could 3D concrete printing be the most useful in construction? As printing for formworks and scaffolding, which are later reinforced and filled with classical concrete? As printing for architectural details such as parapets, designer facade elements, and other not statically relevant construction elements? Or for exteriors, like benches, pergolas, fountains, supporting walls,...? Or in infrastructure? for drainage canals, canalisation, manholes, other constructions on a bigger scale? 
8. It seems that the robots for carving wooden structures are very popular right now. What is their applicable potential?
9. Which of the different subfields of construction robotics will first enter the mainstream? What robots will we see on the construction site en masse first? The drones, 3D concrete printers, something else?