Water drainage is still going to be a big problem, as is damage/scratching caused by shoes, bicycle kickstands, trolleys, anything else with wheels that is push

Water drainage is still going to be a big problem, as is damage/scratching caused by shoes, bicycle kickstands, trolleys, anything else with wheels that is pushed/pulled, you name it. Plus the simple fact that most sidewalks (at least here in the city) are often in the shadows of buildings. It only makes sense to start thinking about sidewalks once you've covered all the roofs, which are way better in every sense.