The Samsung Galaxy Watch4 and Watch Active4 are expected to be announced in the second quarter of this year (April-June). They may mark an important shift in strategy for Samsung as the company is expected to replace Tizen with Android.
It appears that the 3C has certified a 240 mAh battery for use in the SM-R880, which is presumably the 41mm version of the Galaxy Watch4. For comparison, the 41mm Watch3 has a 247 mAh battery, the 45mm one steps up to 350 mAh.
3C certification for the EB-BR880ABY battery for the upcoming Galaxy Watch4
This certification also suggests that the new smartwatches will be unveiled sooner rather than later at some point in the next three months.