I'm a bit surprised this hasn't been made into a movie yet, given the low cost of shooting mostly in one location, and the success of movies like "Buried", "127 Hours" and "Devil" which were all set in confined spaces. Not to mention the Stephen King name!
There's been 'Brake' also recently, which takes place in the trunk of a car. There have been a lot of these lately, you would think if ever there was a time for 'Gerald's Game' it was now.
Gerald's Game could be made into a very harrowing movie. Call me a dreamer but I'd think that after a while the male audience would be able to move beyond ogling the woman's breasts. Years ago, my in-laws saw "Jodie's Body", a play performed by a completely nude middle-aged woman. After a few minutes they said they no longer thought at all about her being naked and just focused on the dialogue.