Chromebooks are likely to feature eSIM support in the future, as a new Chromium Gerrit reference has now been spotted stating as much. In fact, the comments also reference "Hermes" as the codename for a project representing Google's general intention to enable the Chrome OS platform with eSIM support. Highly suggesting this is now something Google and the Chrome OS team will be actively working on going forward. At present, there is very little additional information provided on this beyond the confirmation of Hermes and its general premise.
Interestingly, this was first spotted by XDA-Developers who at the time took a screenshot of the comment which seemed to suggest that in addition to eSIM support, Project Fi support is also now on the Chrome OS agenda. Since then, however, it seems the comment has been edited and the mention of Project Fi has been removed. Whether or not that means Project Fi support is indeed coming to Chromebooks, remains unclear. Although with eSIM support on-board it would make sense for Project Fi support to also be available. At the very least, available to some Chromebooks.
Adding a cellular connection to Chromebooks is not new, as some models (most notably a very popular HP Chromebook) came with cellular support. However, the previous implementation was through the use of a physical SIM card. With the clear suggestion eSIM is now on the horizon, this will be a vastly different thing as eSIM allows for a cellular connection in the absence of a physical SIM card. Which typically also allows device owners to switch between carriers much easier, and allows manufacturers to continue to design and build devices without having to factor in a SIM card slot. Physical SIM or not, the use of a cellular-connected Chromebooks have been limited in the past with only a very few models supporting the technology. Which seems likely to be what Google hopes to change in the future with Hermes. As for when in the future, there are no indications this will happen in the near future, with the comment itself suggesting this is something currently in the very early stages of development.