These ideas aren't new. I doubt that they are impossible but we haven't yet solved the technical problems that would make 'vertical farms' cost effective over regular farms. If farmland became expensive enough (really expensive,) I could see them seeming more viable.
If these were to happen, my entirely uneducated guess would be that it would start with rooftop farming, and that extending to storied greenhouses at the tops of skyscrapers. Depending on your crops, these both don't need artificial light and could lead to solutions for other engineering problems such farming would involve.
I assume rooftop gardening is a completely different (and good) idea. There you have the sunlight already, just being reflected or absorbed as waste heat, it's simply a materials (weight) and cost or species issue. (also it's easier to design for one than retro-fit one on).
If these were to happen, my entirely uneducated guess would be that it would start with rooftop farming, and that extending to storied greenhouses at the tops of skyscrapers. Depending on your crops, these both don't need artificial light and could lead to solutions for other engineering problems such farming would involve.