My zoo buries them on the premises. I know of a camel, a moose and a few other things got buried there. They have a large plot of land that is used to dispose of organic waste like branches and trees, old compost, etc until it’s full and needs to be tricked out to the landfill. They just bury the animals under the ground there.
One thing I never see addressed with the dream of ending cars and just having bikes is how do first responders operate? How do you transport unconscious people to the hospital? Put out an apartment fire? Get to an armed robbery in time to stop it?
Bikes are great but they also aren’t an end all be all solution to society.