A good generality, but I'll disagree on the bakery/sandwich specifics.
There's a lot of overhead in a sandwich shop hiring a baker, then outfitting a kitchen to efficiently bake bread at scale. And how do you handle his days off, with n=1 baker?
Vs. a bakery only needs 4' of counter space to do a modest volume of basic (cold cuts & such) sandwiches. Unless it's a pretty upscale bakery, the customers will be fine with less-than-fancy sandwiches at less-than-fancy prices - those are mainly a "while I'm here" convenience. Vs. a "great sandwich" shop has to qualify as a destination.
I think you're missing the point. The bakery would have to sell "less-than-fancy" sandwiches, but the sandwich shop could sell sandwiches with bread just as good as the bakery would use.
The bakery has to become a inferior sandwich shop to make sandwiches. The sandwich shop doesn't have to become a bakery to bake just the types of bread that they need to wrap their sandwiches.
The bakery would be better off selling dough to the sandwich shop.
I agree here. I more often see bakeries selling sandwiches that they make in house (although no clue as to the volume/financials of it), but rarely (never?) see sandwich shops doing in-house baking. The independent ones out-source to a bakery and if it's a well known bakery, they will advertise where they get their bread.