Larian seems to like to finish a project and move on (while continuing to support it of course). So, I think the *plan* was to go do something else next, but I suspect the huge response to BG3 and dollar signs in Hasbro's eyes may be altering the calculus here.
I think it's quite likely that they might decide to first take a year to do a BG3 expansion before moving on to whatever's planned to be next.