The rights to the Terminator franchise are up for sale again, but there probably isn't that much reason to worry about whether or not there'll be another movie. After all, there have been many owners of the rights over the years, starting with Helmdale Films and producer Gale Anne Hurd in the 1980s, each of whom owned a 50 percent stake.
Next came Mario Kassar and Andrew Vajna's Carolco Pictures, which picked up Helmdale's half in 1990. When Carolco filed for bankruptcy in 1997, Vajna and Kassar formed C2 Pictures and bought the rights again, also acquiring Hurd's 50 percent. Then in 2007, they sold the rights to Derek Anderson and Victor Kubicek, who apparently own several companies that all have some piece of Terminator and that are also all in bankruptcy.
The L.A. Times reports Anderson and Kubicek probably have many options for Terminator, such as taking on investors or just selling the franchise outright. There is no word yet on how this will affect Terminator movies 5 and 6, which Terminator: Salvation director McG is working on. But even if those movies don't go forward, as history shows, it's a safe bet that whoever ends up with the rights will figure out a way to make another film.