I am a huge terminator movie fan, and I am quite worried that they will manage to ruin this. The trailer was lame as hell (it was on before LOTR: TT too). Trailers are often pretty lame, so hopefully this doesn't nessecarily mean the movie will suck. The trailers for T2 were pretty lame if you go back and watch them... Certainly isn't a good sign though...
As for the story of how Skynet/the war could still happen, I can think of a few ways. Number one, Arnolds hand and half of his arm were left in the gears at the factory at the end of T2 (the hand itself wasn't even actually in the gears getting crushed, should be intact). Beyond that, there could have always been another high up guy at Cyberdyne that had information files/prototype stuff in his personal home or at a alternate secret lab or something. Obviously there were setbacks, skynet couldn't have gone online when it original did after what happened in T2. Which would explain why the next movie will now be taking place after the war was supposed to already have happened...
Plenty of stuff they come up with that would be decent to answer all that IMO. I'm just worried the movie itself will suck. I mean the whole female terminator thing is gimicky as hell. And this electrical based terminator or whatever the TX actually is could be lame anyway, on top of it being a petite feminine woman portraying the machine.
No matter what I'll be going to see it, but that doesn't mean I won't be prepared for it to suckass... My last Arnold movie I pay to see if they manage to ruin this.