Well Wenger hasn't been needing the boot for 13 years. It does show how cut throat the life of a manager can be though, Wenger has been well protected in his bubble.
I'm not sure what's better, relentless underachievement or a year of glory followed by a down year and rebuilding. Chelsea are a better example than Leicester though, as I don't think they were ever in danger of going down like Leicester are.