A new leak indicates that LG has successfully attained trademarks for names that sound like flagship phones to be released after 2020. There is no G11 or G12, however: instead, they appear to fall in line with the Vx0 phablet line. Therefore, the G10's successor may be called the G20, and so on.
https://www.notebookcheck.net/LG-trademarks-its-post-G9-flagship-names-in-advance.427294.0.html