NEW YORK — “I'll be back,” the line Arnold Schwarzenegger first uttered more than 30 years ago in that indelible manly monotone, belongs to the Terminator, of course. But it also might as well be the official slogan of the summer movie season. It's the time of year when Hollywood's older, reliable brands, with the tenacity of Schwarzenegger's lethal cyborg, claw their way back onto the big screen in a popcorn parade of big-budget sequels, reboots and re-dos. That's nothing new, but the extent of the sequel spinning is. The sequel expansion — as headlong as Tom Cruise in the “Mission: Impossible” movies — runs in all directions, stretching into prequels, second-try reboots, spinoffs and franchises that are less linear, roman-numeral progressions than (as in the brimming Marvel world) whole universes of overlapping characters: fantasy realms to visit, not just stories to follow. To fuel the proliferation, Hollywood is dipping ever deeper into its vaults: 10 of this summer's most anticipated blockbusters have origins dating back more than three decades, including “Fantastic Four,” “The Man From U.N.C.L.E.,” “Mad Max: Fury Road” and “Terminator: Genisys,” the fifth film in the series created by James Cameron in 1984. Schwarzenegger is back to say that he's back. Nostalgia and familiarity mingle with updated special effects and new cast members in these films to render something that hopefully feels fresh to moviegoers. As the “Fast and Furious” series (more profitable in its seventh installment than ever before) has proven this spring, the lifespan of the sequels no longer adheres to the old rules of inevitable decay — at least for now. The ever-lengthening life of franchises can make for some strange off-screen realities, and not just for 67-year-old Terminators. “Mad Max: Fury Road” (May 15), is returning decades later with its original creator, the Australian director George Miller. There is blunt mathematics behind the proliferating franchises. The top six summer films at the box office in 2013 were sequels. Last summer, all of the top 10 movies were sequels, reboots or hailed from well-known properties. This summer, the box-office seems nearly certain to be led by “Avengers: Age of Ultron” (May 1), the sequel to the 2012 superhero team-up original, the highest grossing-summer movie ever. With $1 billion-plus in box office assured, the financial imperative is, of course, enormous. While Marvel's “Avengers” marches forward (a two-part sequel is planned), it is joined by a handful of sequels that come from fairly recent films: the teen musical “Pitch Perfect 2” on May 15; the “Despicable Me” spinoff “Minions” on July 10; Seth MacFarlane's comedy “Ted 2” on June 26. But the bulk of the summer season will depend on older franchises, some of which are counting on moviegoer amnesia. “Jurassic World” (June 12), stuck in development for a decade, is the fourth installment in the franchise that has been dormant (but not extinct) since 2001's “Jurassic Park III.” Its star, Chris Pratt, led last summer's runaway hit, “Guardians of the Galaxy.” “Fantastic Four” (Aug. 7), starring Miles Teller and Michael B. Jordan, is an attempt to reboot the Marvel foursome after the little loved “Fantastic Four” gave it a go just 10 years ago, and was followed by a 2007 “Silver Surfer” sequel. The futuristic “Tomorrowland” (May 22), directed by Brad Bird (“Ratatouille,” “The Incredibles“) and co-starring George Clooney, comes from the producers behind “Pirates of the Caribbean” and hopes to turn another Disney theme park attraction into a massive franchise. “Mission: Impossible Rogue Nation” (July 31), the fifth entry to the Tom Cruise action series, isn't the only film trading off an old television show. “The Man From U.N.C.L.E.” (Aug. 14) is Guy Ritchie's take on the ‘60s spy series. HBO's “Entourage” (June 5) will also get a big-screen swan song about four years after the show's finale. — AP