"Too much traffic"
I really cannot imagine what ir must be like to write about a character for seventeen books. Full stop.
The most extreme recent example I can think of was Lewis Trondheim's Lapinot adventures (French bandes dessinees). After 7 or 8 lighthearted, sentimental adventures, and seemingly in the midst of a severe depression, he killed off the main character in the final book, as well as having another character get cancer and another be put into a coma. The main character also breaks up with his long-time girlfriend before dying. Trondheim then gave up comics for several years.
If you really want some light reading and I mean light reading to clear your palet and laugh out loud and not be able to put it down because it's really funny and a great page turner. Check out Taylor Wilshire's, "The What-if Guy" that comes out in October. or check out www.thewhatifguy.com. It's a chick lit with a spiritual twist, not your think-you're wrong.
It's not a good idea to kill off Rebus. Put him into retirement or whatever. Years ago Nicolas Freeling killed off Inspector Van der Valk and then bitterly regretted it because no one read his later crime series. He had to resort to using Van der Valk's wife as a sleuth.