Franchises die when the creation process starts with "We need a new film, get me some ideas". Good films always start with someone going "I have an idea, let's try a film!"
Terminator 2 was great because Cameron had all those ideas ready. Terminator 2 is what Terminator 1 would have been like had the technology been there already, so Cameron put all those ideas in some drawer and ten years later did the film he always wanted to do to begin with.
Terminator 3 and 4 are the result of producers saying "We need a new Terminator film. Go make shit up."
And Terminator 5 will be no different.