Google's plan to restrict sideloading on Android has a potential escape hatch for users
(www.androidauthority.com)
This isn't "my idea", this is how the industry already does code signing. You can't sign something with a date of 1984 because your certificate has a start and end date, and is usually only valid for 1 year.
You can read more about how this works here: https://knowledge.digicert.com/general-information/rfc3161-compliant-time-stamp-authority-server