No Arnold...no way... Not saying that Arnold should star in terminator 4-6, let's face it, I doubt he's willing to get back on gear. I am saying, however, is let it die. Anything after the ending of Terminator 3 would be anticlimactic. Which happens to be up there as greatest movie endings of all time, alongside the likes of Fight Club.
Well, they cant really let it die, not with the ending in T3. I agree that it wont be the same without Arnold, however dont look down, it still may be a masterpiece, if they choose to do the work right, and not just to cash in.