Still in the end if the martians had been able to control the orbitals around earth invading really would not be necessary. They could demand unconditional surrender or just start dropping rocks till the earth quit. The whole invasion of earth was not a question of taking out the whole thing it was basically planning for drop insertions to capture some specific points.
If GoT hits around April, which every season did except 7, it should wrap about the same time The Expanse airs assuming they keep the same release schedule they have for seasons 1-3. S1 Dec '15 > S2 Feb '17 > S3 April '18 > S4 June '19?
Yup it is pretty much needed to demonstrate yet again how powerful they had been and what happened to them. My concern is also the FX shots really most of the seasons are done in ships or stations so you can reuse a lot of sets all the time and its fine. But book 4 is going to take some serious sets or FX time do pull off or there would be no point in doing it.
Actually yeah come to think of it, that almost certainly contributed to Syfy cancelling it right before it gets to Cibola Burn.
I'm sure the SyFy execs read the book, realized all the FX shots on the planet, in orbit, underground, and the big events at the end and NOPED the fuck out of the massive budget it would require to film.
The one plus to amazon though is they don't have to fit the season to a television schedule filled with mid-season breaks, holidays, and other interruptions. Releasing the whole season in July is still basically a one year gap between seasons.