Where to go from here?
If you have not seen Salvation yet, I wouldn't come in here for fear of some spoilers finding there way into the thread.
So, just as the title says, where does the franchise go from here? Personally, if I were setting up for the next movie, I'd try to have the world look like it did in the Cameron films; wreckage and skulls everywhere, and a feel that humanity truly is backed up against a wall. To do that, I'd actually have the plot be based around humanity running out of resources such as metal bullets, submarines, helicopters, etc, and John Connor leading a raid against a Skynet factory in order to acquire those sweet plasma/laser guns that we saw in The Terminator and T2. This, of course, would have to be set a few years after Salvation, perhaps in 2022-2024, which has enough time to deplete the Resistance armory but still have enough time before Skynet sends the first Terminator back to kill John Connor. Also, I'd have John Connor say that after they destroyed the Skynet factory, that humanity was hit with retribution from the machines, with many pockets of Resistance being destroyed within weeks of that attack. I think that would be a good way to bridge the gap between the technology witnessed in Cameron's work, with the technology in Salvation.