As sensor technologies continue to develop, the cost of these sensors will decrease making them more and more cost efficient and more applicable. These sensors could be placed on trees, vines, or in the ground in areas to measure all kinds of important environmental information. This information could be monitored and relayed to an autonomous vehicle that would be tasked to perform a specific action for that specific area.
"Scalability will be limited by serviceability - service and support is critical." @RobotCEO
For autonomous vehicles to really move into many various facets of everyday life, scalability will be limited by serviceability. Diagnostics must be reliable and quick to identify any potential issues a system may encounter - then be able to get someone on it quickly to correct the problem.