At this point, since Avery joined the army before 9/11, he's somewhere in his 40s, or very late thirties at best.
These types of protagonists in action thrillers can generally continue indefinitely, and often do, if they're profitable. While Mitch Rapp's lack of aging isn't something I care or think about as a reader, age and literary longevity is something I've been thinking about when it comes to my own character and series.
Other authors, like Daniel Silva, who have aging protagonists have been making a point of saying the new story is set just days, weeks, or months after the previous one, but one can only keep that up for so long.
From the first book, I'd always intended that at some point Avery will need to retire and fade into the background, likely to be replaced by a new character, who has not been introduced yet, but he won't necessarily need to retire from my writings.
Inspired by David Hunt and RJ Pineiro's book, WITHOUT FEAR, which is a historically-set prequel to their contemporary novel WITHOUT MERCY, I've been toying with the idea of setting stories within the past decade or two, both as a means to keep Avery alive, as well as to cover subject matter that's interesting to me but no longer topical or current. For example, I have a story in the back of my mind that involves Ghaddafi's WMDs during the 2011 Libyan Revolution.
Either way, that still's not not likely to happen anytime too soon, so we shall see.
