I have a feeling Mr. McG will not get the director's chair on the next one. Hell, there may not even be a T5. Personally, I think the franchise is way past its prime...the TV show failed and the new movie isn't even the blockbuster that the third one was. That's pretty bad IMO.
Mind you, I enjoyed the new movie and found it entertaining. I just think it's time for the Terminator to retire.