Will five make the franchise come alive? Or will audiences give it a summary execution, saying, "You have been targeted for termination"?
There is much at stake with Terminator Genisys, which opens tomorrow. It comes after movies three and four, both of which were snubbed at the box office and by fans of films one (The Terminator, 1984) and two (Terminator 2: Judgment Day, 1991).
But things have turned a corner, say the two people most intimately connected with the series. Both Arnold Schwarzenegger, the T-800 himself, and James Cameron, cocreator and director of films one and two, have declared in recent interviews that Genisys is the true successor to film two, while at the same time, deriding films three (Terminator 3; Rise Of The Machines, 2003) and four (Terminator Salvation, 2009).
The Austria-born actor is back as the protector cyborg in Genisys, while Cameron is not involved (Alan Taylor, director of 2013's Thor: The Dark World, helms the new instalment).
While fans of the sci-fi classic (myself included) desperately want both of them to be right and not simply parroting public relations poppycock, there are signs that the latest in a line of movies about time-travelling killer robots could arrive with dead batteries.
No advance screenings of Terminator Genisys for Singapore media were arranged - this is usually a sign that the studio wants to keep reviews out of the public eye for as long as possible.
And they do this because they think reviews will be as sharp and cutting as the arm-blades on a T-1000 liquid metal robot (played this time by South Korean actor Lee Byung Hun).
The second hint that things might have gone awry is the last film's long gestation - six years.
The title of the fourth movie, Salvation, carried a load of irony. After the box-office failure of the work - famed, more than anything else, for the Christian Bale on-set rant that went viral on the Internet - one stakeholder after another either went bankrupt or passed.
Salvation, directed by McG, was supposed to be the reboot of the series.
In keeping with current tastes, the revamped franchise was going to focus on leader of the human uprising John Connor, an angsty hero in the vein of Batman. Bale, the ultimate angsty male lead, was Connor. It was to be set in a grimy dystopian future filled with cool killer machines.
That formula failed.
What resulted was a confused tangle featuring too many characters and a story that tries to justify a meandering tale of action and violence with a cynical final act, centred on, for goodness sake, a heart transplant, carried out in a tent open to the elements.
That forced uplift in the ending was completely out of character with the tone set in the first two films.
The other clue that not everything is as it should be lies in its rating. In the United States, the first three movies were given an R rating, which means that those under 17 have to accompanied by an adult.
Salvation, however, in keeping with current summer blockbuster trends, moved it to PG 13 (parents are cautioned about some inappropriate material) and Genisys is following suit.
Can a Terminator movie be a Terminator movie without the machines demonstrating their specific and intimate methods of killing?
What would the second film have been like if the shot showing John Connor's legal guardians skewered by the T-1000's arms had been cut to fit PG13 limits?
So what are the magic ingredients that made the first two films special?
For one, there was never any doubt that humans were soft and vulnerable, while their opposition were nightmarishly relentless and indestructible.
Even after Sarah Connor (Linda Hamilton) had grown into a super-soldier by film two, she would need all her wits and the help of the now-friendly T-800 (Schwarzenegger) to keep herself and her son John (Edward Furlong) alive.
Film three had an antagonist, the new-model T-X (Kristanna Loken), a machine that never carried the same sense of threat, while film four turned the malevolent Skynet artificial intelligence network and its robots into a sham force resembling the Star Wars Imperial Army - lots of impressive hardware, but easy to destroy en masse and with no one able to shoot straight.
The other ingredient is the balance of characters. Films one and two had people the audience cared about because they were a family (mother Sarah and son John, with father figure the T-800) forced to meet an insurmountable challenge.
That was changed in film three, when the studio decided that family was out, and the love story of sulky loner Connor (Nick Stahl) and bratty veterinarian Kate Brewster (Claire Danes) was worth caring about. The fourth movie opted to throw characters out in favour of five-storey-tall computer-drawn robots going smashy-smashy.
If there is one heartening bit about the new movie, it is that Sarah Connor is back, in the form of Emilia Clarke (from HBO's Game Of Thrones). Sarah, the link between the world we live in now and the horrible future to come, has always been the audience's point of contact.
Let's hope they treat her with respect this time, or it's hasta la vista, baby.
Terminator Genisys opens June 25.
Check out other movies that are opening in cinemas on June 25 here.