Probably a bigger body is necessary to make things possible "beyond expectations". "Creators" and "technology, technology, technology" in mind, what could that be? 4K/60, 10-bit 4:2:2 + X = 8K? BOSS/Olympus/gimbal like image stabilisation? Computational video, with electronic bokeh control, hdr video? Or, to exceed my expectations towards Sony engineering at all - better ergonomics/user interface??
I don't expect Sony to release such sort of camera before 2020. And I don't expect it to be named A7S III.
But in the meantime, why shouldn't Sony release a A7 III with "easy to add 4K/60"