Or if an actor is called back months after shooting wraps to redo a scene but has put on some pounds in the meantime? Directors could just bring in the digital doppelganger.
Another reason humans aren't likely to go away anytime soon: Even the priciest, most temperamental actors seem like a bargain compared to digital ones.
It took more than 200 animators, programmers and producers from 22 countries to create Final Fantasy. The estimated bill for their four years of labor: $115 million.
"It's so ... cost prohibitive," says Fred Raimondi, animation director at Digital Domain, James Cameron's special-effects shop.
In 1999, Motorola hired Raimondi and his crew to create a digital spokeswoman for a new ad. The result was Mya, who made her debut in a 60-second spot during last year's Academy Awards ceremony.
Mya took several dozen animators several months and nearly $1 million to create. "It takes God nine months to create a human," says Raimondi. "It took us almost as much time to create Mya."
In the end, her creators still had to hire two people - model Michelle Holgate to be the model for Mya and former Beverly Hills, 90210 star Gabrielle Carteris to be her voice.
"At the end of the day, ain't nothing like the real thing, baby," says Raimondi.
"Especially when it comes to supermodels."
Special effects in film
Some of the highlights of technology in film:
1982: Tron (Walt Disney Studios) - The first major computer-animated film, it featured more than 53 minutes of digital FX. Its lame plot, however, made it a flop.
1986: Max Headroom becomes first computer-enhanced pitchman for Coca-Cola. Max is a h-h-hit, eventually landing his own ABC-TV show.
1988: Jeff Kleiser and Diana Walczak create the first all-digital actor in their experimental short film, Nestor Sextone for President. A year later, they coin "synthespian" for synthetic thespian.
1993: Jurassic Park (Universal) - Its digital brontosauruses and velociraptors often stole the show from the human actors.
1995: Toy Story (Pixar/Disney) - First film created entirely by computer.
1999: Star Wars: The Phantom Menace (Lucasfilm) - Digital co-star Jar Jar Binks often acts better than co-star Liam Neeson.
2001: Final Fantasy (Square Pictures/Columbia) - First film to feature cast of photo-realistic computer-generated human characters.