Samsung's next Gear smartwatch to run Tizen, is codenamed 'Solis'
Samsung had codenamed the Gear 2 'Orbis' - Latin for 'circle'. The next one is codenamed 'Solis' - 'Sun'. This means the roundness of the next Gear smartwatch should not be doubted.
Something else hasn't changed, the OS. Current information points to Tizen and there's no word on an Android version. The original Gear S had such an alternative - the Gear Live - but the second-gen smartwatch is Tizen-only.
Along with the codename, model numbers for the Gear S3 are known: SM-R760, SM-R765, SM-R770, SM-R765V, and SM-R765S. The last two should be carrier versions (Verizon and Sprint, maybe?).
That's about all we know about the Samsung Gear S3. It will have a limited edition de Grisogono version, so bling is covered.