Why do people keep saying this? Mummy's ride system isn't "old" by theme park standards. It also isn't "complicated." I've heard rumors that Premiere won't "support" the ride anymore which is completely false as well. Premiere has three coasters currently under construction and even if they went bankrupt tomorrow, any number of coaster manufacturers could step in and support the ride after some minor alterations. Flight of Fear, Mr. Freeze, Joker's Jinx, Poltergeist, all Premiere launch coasters, all MUCH older than Mummy, all still operating.
Tower of Terror is a DECADE older than Mummy and has a ride system that requires far more upkeep. Even when Disney was considering their options for the DHS version, tearing it down wasn't on the short list of ideas.
Rides don't age in years. They age in hours/cycles.
Joker's Jinx opened in 1999, so has been operating for 20 years. Now, Six Flags America is a seasonal park, and typical opens 3 days a week between Easter and Memorial Day, 7 days a week between Memorial Day and Labor Day, and three days a week in October. I did an extremely rough calculation based on those things and figure the park is open about 170 days a year. For the sake of math, I'm going roughly say the park is open 10 hours a day, so the Joker's Jinx runs 1,700 hours a year.
Over 20 years, based on those calculations, Joker's Jinx is 34,000 hours old.
Now, Mummy opened in May 2004, it's been running over 15 years. Big difference is, apart from refurbs (which it rarely gets), park closures and break downs, it's running every day. But, for the sake of argument (and easy math), let's knock a year off it's total "age" and (to account for the aughts), I'll say it only ran 9 hours a day.
9 hours a day * 365 days a year * 14 years = 45,990 hours old.
So, even though Jinx is old by opening date, these conceptual calculations show Mummy has almost 11,000 hours of more tear. It would take Jinx 7 more years (based on how it operates) to get to the same wear level.
But, let's extend this thought experiment. Let's say Mummy closes in 2025 without a refurb (so, 5 more years), and the park now runs it 10 hours a day.
10 hours * 365 * 5 years = 18,250 hours. That puts it at 64,240 hours of approximate run time before closure.
Based on Six Flags seasonal operations, it would take Joker's Jinx another
17 years to get the same amount of total run time.
So, a ride at Universal that last twenty years can last thirty-five to forty years in a seasonal park. That's why they operate on a different time frame. For reference, Hulk was replaced at approximately 45,000 hours. Dragons closed at over 50,000 hours.
One of the big differences between Disney and Universal is that Disney will take down their signature rides for a few months for refurbishments. That extends their lifetimes. Universal can rarely afford to do that.