The successor to the Galaxy S10 will be named Galaxy S20 . This is at least supported by the trusted leaker Ice Universe in a recent tweet. Its rationale is that the S20 has been inspired by 2020, the year that the device will be released, showing Samsung a direction to simplify its device names to keep up with the year that is released, making it easy for users to understand which device they are buying. It also highlights the new step Samsung will take with the new device that will have major technical differences from the previous one.
In addition, in marketing terms, by choosing the S20 and omitting the S11, Samsung moves ahead of Apple in the numbering of the models. Huawei did the same, which went from P10 to P20 in 2018, omitting P11.
So far, however, nothing has been announced from an official source and we do not know if this is something that is being discussed within the company or is something that has been decided.