Like what? I'm honestly curious about what McD's stuff would be irrevocably damaged by creative subbing. Esp in a 3rd world situation where you don't have a lot of options.
There are proprietary food receipes and ingredients, I'm sure, but many of those could be creatively substituted for over the short term.
The branded non-food items are often more important to the image that a chain eatery projects. Everything from advertising to signage, packaging materials, cups and cutlery, interior decorations, etc. The list can be very extensive.
For some companies, there are special tools and equipment used to prepare food items unique to that establishment. If those tools cannot be repaired or replaced, then signature food items go off the menu.
If important brand-establishing items go away, then so does the brand. If the brand goes away, then so does much of the original appeal for patronizing an establishment.
In this case the only thing left would be the "McDonalds" sign over the door. Everything else about the place would be different, non-brand. It wouldn't be "McDonalds" anymore.
Edited to add:
Mind you, I am not saying Mickey D's is a good place to eat. In truth, I can hardly stand the joint, and eat there only in extremis.
