Franchise failure rates don’t bear out that being a real risk. However, McDonald’s is publicly traded, and investor pressure to improve at the margins may make a business that is fundamentally well served by being change-averse do stupid things.
Other chains have had lots of franchises fail though. A&W used to be big. Long John Silvers. Are you saying McD specifically can’t fail? Or that none can?
Kmart once had 2,323 stores in the US, and today they have just this one comical one[1] (the picture is worth it, trust me).
Nobody's too big to fail, and the way you fail is by making no innovation in your business, not doing optimizations that smarter competitors do, etc. (which was exactly what Kmart spent the 80s and 90s doing).
McDonald's would absolutely decline if they simply abandoned all 'loyalty program' ideas, while every competitor leverages them, because those competitors will take customers away little by little. Fewer customers, less money to justify renovations, less people want to open new franchises in the best spots, leading to fewer customers, in a cycle.