Before HAWAII FIVE-O, Jack Lord was Felix Leiter to Sean Connery as James Bond in DOCTOR NO; Cec Linder replaced him in GOLDFINGER, but didn’t live as long.
(You ever wonder what a typical Bond movie must look like from Leiter’s perspective? “Huh, once again it’s my in-over-his-head buddy who doesn’t know what’s going on; figure I’ll bring him up to speed, and then watch as he runs off to get captured like always, and then after a nice steak dinner at the local hotel I’ll send in the Marines.”)
Ethel Merman originated the role of Mama Rose on Broadway in the musical Gypsy. Rosalind Russell played the part in the movie (to the undying indignation of Merman’s many fans.) Russell died in 1976 but La Merm soldiered on, singing to the end, until 1984.
…and, come to think of it, Donald Pleasence was replaced as Blofeld by a younger and more vigorous Telly Savalas, but it’s the smaller and older guy who lived longer.
There was a remake of the Munsters TV series in 1988-91. Al Lewis was very disappointed that he couldn’t resume his role as Grandpa from 1960s. He commented on how “Grandpa is now too old to play Grandpa”. He outlived his replacement, Howard Morton who was only two years younger, by nine years.
Audrey Hepburn played Eliza in the film version of “My Fair Lady” which Julie Andrews played on Broadway (and there was controversy about that). Julie is still with us, sadly Audrey isn’t.
How about a Trapper John three-fer? Elliot Gould, who played Trapper in the film version of MAS*H, has outlived Wayne Rogers, who played Trapper in the TV series. Rogers outlived Pernell Roberts, who later starred in “Trapper John MD”.
Not exactly a replacement, but… Hitler’s bodyguard Rochus Misch was played by Heinrich Schmieder in the 2004 movie The Downfall. Schmieder died at age 40 in 2010, Misch died at age 96 in 2013.
Robert Duvall has outlived his Major Frank Burns counterpart Larry Linville (d2000).
Carl Gottlieb has outlived John Orchard (d1995) despite being cast as “Ugly” John.
Bud Cort has outlived (just barely*) one of the two TV actors of Pvt. Boone. Bruno Kirby (d2006) had the role in the pilot, Robert Gooden in a few other episodes might still be with us.
*Cort was nearly killed in a 1979 car accident that left him scarred.
Carol Channing played the original Dolly Levy in Hello, Dolly on Broadway and has outlived several of her replacements from the original run: Pearl Bailey, Phyllis Diller, Betty Grable, Ethel Merman, Martha Raye, and Ginger Rogers.
Buddy Ebsen (d. 2003) who played Jed Clampett in the TV series The Beverly Hillbillies outlived Jim Varney (d. 2000) who played the character in the 1993 movie remake.
Ebsen was also originally cast to play the Tin Man in The Wizard of Oz but he turned out to be allergic to the silver make-up and was replaced by Jack Haley (d. 1979).