Samsung appears to have confirmed an impending successor for the Galaxy S10 Lite. A device with a name to match this description has appeared alongside existing devices on development websites for the US and German divisions of the OEM. They suggest the upcoming phone will run Android 10, at least.
https://www.notebookcheck.net/Samsung-lists-the-Galaxy-S20-Lite-by-name-on-updated-software-support-pages.491415.0.html