The wooden structures and building stuff is amazing, and is great for early base building. I think that blueprints should be available to find for concrete alternatives to all wooden structure pieces. You'd have to find the blueprint, study it, and then you can use Stone or some other material to convert an existing piece (such as a wall, or a door) to the Concrete alternative. Concrete would be much much stronger, but would be more time consuming to upgrade an entire base piece by piece to concrete.
What do you guys think?
I wouldn't put it past them to make it happen eventually, but at this point features, actual models, and bugfixes are more important than a new building material, I think