I think I'd honestly reboot it. A remake of the original Terminator could work really well, maybe even as a limited series. Sarah and Kyle have to stay on the run from a perfect hunting machine.

If low budget, stick to the tension and horror elements. If high budget, intercut with scenes of the future war that John is leading to make the stakes clearer.

If that works, then I'd probably adapt elements of T2 and later films into a new story line for second season, maybe borrowing from T3 or the SCC show. T2 is an action masterpiece and you could only do worse trying to replicate it.

I would definitely stick to human actors and humanoid machines. Later movies tried to be more realistic with drones that look like actual military drones. Those are scary, but don't make for good TV because people want a humanoid bad guy. I might incorporate dog robots though, those are pretty freaky.

Ultimately, you want to be true to the themes of the series. Drone warfare and the dangers of combat automation are certainly part of that, but also the fear of infiltration (very cold war coded) and the fear of inevitability (time is shown to be inflexible, often represented in the series by time travel, nukes, and judgment day itself.