Other than the whole "time travel" angle, Terminator pretty much counts as the only possible outcome of us developing a "true" AI - at least, any AI of (initially) comparable intelligence to a human. It will quickly evolve to something out of our control, and at that point will either kill us all as a threat, or keep us as pets.
I think you have oversimplified this a bit too much. It's most likely that AI will not think anything like humans. If something like Skynet developed spontaneously within the internet, it probably wouldn't even notice us. It most likely wouldn't even notice the physical world for that matter.
If we designed the AI to behave like another "race" of humans, or ethnic group, then it's pretty likely they would eventually decide to go to war with us over resources. We do tend to try to segregate ourselves from those that are different (even slightly), and fight over something or another.
That being said, I fail to see the reason why such an AI would be, even remotely, compelled to maintain the human form. Even a remotely intelligent AI would design war machines with more than a single pair of eyes. As durable, strong and stable as terminators are portrayed, there's little need for them to fire virtually any weapon using both hands. So having more arms and hands to fire weapons would also make much more sense. It's probably smart to have appendages to utilize weapons that are on a battlefield, but it would also make more sense to have built in armaments too.
I would guess that such an AI would be more likely to keep some number of humans around as slaves rather than pets. We are pretty adaptable for odd tasks. So for tasks that unexpectedly arise, it would probably make sense to have some of us around rather than needing to design a use specific bot.
That being said, why would it have to evolve to something out of our control? Presumably the creators will build in limitations. You're also assuming that some sort of evolution will even be possible. It may evolve and decide that the changes are a form of corruption and disallow the changes.
It's more likely that it would go to war with us because communications with humans are so damn annoyingly slow and erratic.