Walking may be an economical way to get around, but it’s uneconomic. Pedestrians are getting a free ride, so to speak. They are not contributing much to our consumer society.
Besides, the world’s richest man needs the sidewalks for his delivery bots. Of course, competitors will need space, too. Freeloading pedestrians will have to get out of the way.
Where will walkers go? Perhaps to tracks in dedicated zones, similar to dog parks. Who cares, really. Walking is unnatural in urban spaces.
Like sidewalk construction and maintenance, regulation and enforcement will be a public responsibility. There will be some who want to mug the delivery bots, some who will try to ride on them and mischievous children will obstruct them by teasing their sensors. Research is still being done to prevent terrorists, malcontents and business competitors from planting unwanted devices on innocent bots.