>>13214106A single machine can do the jobs of a dozen people in less time, and can be maintained by a single technician. Assuming that China's fertility rate stabilizes at 1.6 we're still at least a century away from total collapse due to demographics only.
I watched this Netflix documentary recently about the Chinese auto-glass factory in Ohio, and it focused on how American and Chinese workers struggled to get along. After finishing it I tried to get an update as to what happened and found out that all those employees were replaced by robots anyway kek.
Automation will take your jobs, not immigrants.