The 69-year-old has enjoyed a steady flow of work in recent years, but she insists it's because she has looked to other areas in Hollywood to perform.
"If you're talking about Hollywood as a studio system, I don't think it's changed," she told U.S. breakfast show Today on Thursday (26Jan17). "If anything, I think it's even more difficult. I think where it's changed is in the world of television, in the world of cable, in the world of all these wonderful mini-series, where a lot of the top writers are now going into that arena.
"Also in independent film, but as far as the big studio movies... (I think there's an expiration date). I'd love to be proven wrong."
The Guardians of the Galaxy actress has starred in several independent movies in the past several years, but she explains the financial payoff is not as significant.
"I do anything (if I like) the script...," she said. "In the last couple of years, I think I've done five or six independent films. I love the work and I love the script and I love the character, but as far as you get a good hefty pay cheque, it's challenging...(sic)"
Glenn is not the only actress who has spoken out about the limited acting roles for women of a certain age in Hollywood - Jessica Lange and Susan Sarandon also feel they are faced with challenges.
The decorated veterans have teamed up to star in Ryan Murphy's new TV series Feud, which is based on the intense rivalry between screen legends Bette Davis and Joan Crawford. Lange is convinced the feud was partially caused by industry pressure.
"(Feud is a) microcosm of what happens to women generally as they age, whether they become invisible, or unattractive, or undesirable," Jessica pointed out while speaking at the 2017 Winter Television Critics Association Press Tour earlier this month (Jan17).