If the rumors are true a change is coming in Samsung’s future plans, there will indeed be no Galaxy S11, but a Galaxy S20 instead, followed by a Galaxy S30, and so on. Remember: the current Galaxy S9, and the upcoming Galaxy Note 9 will mark the last of these models designated by a single digit. Hence, changing the naming convention, if planned, could happen at this very convenient moment in time, and in 2020 we might see a Galaxy S20.
There are also some that believe Samsung might further simplify device names: Samsung A30, Samsung S40, etc., but this would imply ditching the Galaxy brand. Samsung put tremendous efforts in building the Galaxy brand into a successful one (to the point where everyone talks about “the new Galaxy”), which is why we think that this scenario is highly unlikely.
Source