I think it would have worked better if each of the Post-T2 suggested the future timeline was actually being massively shifted and changed, even if a Machine War became a recurring theme; if, say T3 revealed that the Machine War was now more of an chaotic period with different AIs fighting each other as much as humanity, and thus Humanity's fortunes *had* improved a decent amount, that would make the stories feel like they have some power... or if humanity won a much more assertive victory in the future before they could be massacred, and so a new Terminator is sent to start one a decade early, moving that conflict up to when John and others are younger and removing the certainty of causality form the series.