It is disappointing but most likely yes, GoW will be cross platform same as the officially announced Horizon Zero Down sequel.
It's the first time Sony does this. Nintendo was the first one. Xbox followed suit and now Sony.
Of course it has an impact. The Last of US remaster is an example of this. Compare it to The Last of Us 2 (which didn't have any previous gen restraint) and it's clear what the capabilities of PS4 are without being held by previous gen.
All this is a shame. We won't probably look at the true potential of next gen for the next 2 or 3 years.