I was kind of expecting something by fall 2019, myself. I assume they're going to let Filoni take a bit of a breather before he delves into the next series.
Last I heard he'd been promoted to head of LF's entire animation division, so whatever's coming up next he's probably acting more in a supervisory role over a more hands-on creative team, somewhat akin to how Lucas was with TCW.
Indeed, give how conspicuously quiet things have been this last year I wouldn't be surprised if they're not already hip deep in whatever is coming up next. We'll likely not know for sure until this year's SWC.