How ironic that back in 1984, when Arnold Schwarzenegger's lean and preposterously muscular Terminator first made contact with human civilisation, we were told the sinister T-800 "will not stop, ever, until you are dead". Turns out that Michael Biehn's Kyle Reese was correct in one sense, for we seem to have been plagued by Terminators of ever-decreasing vitality (barring 1991's T2: Judgment Day) on the big screen ever since.  But Arnie has now stepped up to let us into a vital secret that might have been extremely useful to John Connor and his army of human freedom-fighters in their resistance campaign against the machines. The Terminators do not in fact go on forever, he told MTV. On the contrary, they decay just like the humans upon whom their cyborg physiology is modelled.  Arnie, who is set to appear as the T-800 once again in next year's Terminator: Genesis, was asked to explain how he planned to portray the same (presumably ageless) robot for the fourth time when he himself had advanced from 37 to 66 since 1984. "The way that the character is written, it's a machine underneath," Schwarzenegger patiently explained. "It's this metal skeleton. But above that is human flesh. And the Terminator's flesh ages, just like any other human being's flesh. Maybe not as fast. But it definitely ages."  Whatever your views on an extremely convenient revision of the Terminator rulebook, there is no denying that the film saga as a whole has been in decline ever since the halcyon days of the James Cameron era. Genesis, as well as restoring Arnie to the series following his absence from 2009's Terminator Salvation (except in CGI form) looks set for an impressive cast. Game of Thrones' Emilia Clarke is in line to play Sarah Connor, with Zero Dark Thirty's Jason Clarke as John Connor and Spider-Man's brilliant JK Simmons as a weary detective who has been chasing robots for three decades.  Unfortunately, we've seen this all before with Salvation, which managed to recruit a post-Dark Knight Christian Bale, Bryce Dallas Howard and Helena Bonham Carter, but still left fans of the series nonplussed. Genesis also has Game of Thrones' Alan Taylor reportedly on board to direct, but the latter proved with last year's Thor: The Dark World that he is no more than a safe, albeit talented, pair of hands.  What Genesis really needs is a film-maker with the vision and clout to reimagine Terminator in a manner which restores it to relevancy. Fans of Cameron's films will probably declare that the series should have been allowed to die a graceful death following the denouement of T2, which saw Sarah and John Connor successfully divert the course of history away from machine armageddon with the help of a friendly T-800 and a few ghettoblasters pre-loaded with Guns N Roses tapes. But this is modern Hollywood, and the money men will never allow a successful franchise to be killed off while it is still stacking up greenbacks.  The answer seems to be a respectful reboot with a polite nod or two to the series' past, perhaps along the lines of JJ Abrams's remarkably successful reworking of Star Trek five years ago. After all, the Terminator saga's sci-fi leanings should allow plenty of room for alternate timelines.  Genesis's title fits the bill, but its suggestion of a new dawn for the series is undercut by rumours that the film's storyline will bounce around between the events in 1991 and 1984 that we saw in Cameron's original movies, a foolish plan unless the film-makers really plan to hold themselves up to an impossible standard. Another suggestion, that the movie will centre on a Terminator sent back to protect Sarah Connor as she grows up, sounds more promising as the basis for a new timeline. But is Arnie's T-800 really the right cyborg for the job?  There is a reason Abrams refused to cast William Shatner's Captain Kirk in 2009's Star Trek reboot, opting instead for the less intrusive figure of Leonard Nimoy's Spock as he sought to reimagine the series with a new cast. By the same maxim, it's going to be almost impossible for Taylor and his team to apply the fresh coat of paint that's so desperately needed to bring Terminator hurtling back to cultural currency when a giant Austrian bloke is leaning menacingly against the relevant wall.  • Ben Child: Please let Joss Whedon take over Terminator
Ben Child: Terminator: Genesis sees Arnie return to his most famous role, but perhaps a reboot wouldn't need to rest on his shoulders