Not offering sandwiches in economy will not have the slightest affect on whether pax choose to fly with BA or not and it most certainly will not bring the company to bankruptcy.
Why should it? other carriers do not offer free sandwiches and their aircraft are full.
People usually travel on the ailines that offer the cheapest fares, from the most conveninet airports at the most convenient times.
I find it hard to believe that some people think all the pax in the tourist cabins of BA short haul aircraft are only there for the sandwiches.
I am a regular pax and notice a lot of pax refuse the sandwiches.
It is crazy anyone thinks people will go out of their way to fly with other airlines from remote airport at sometimes dreadful departure times just because they will not get a free sandwich with BA.
One can always buy a sandwich in the airport and after all you also have to pay for them on the LCC's. at least drinks will be free on BA unlike they are on the LCC's.