Since now the apparent need to commute in has been much reduced, now is a comparatively poor time to be trying to operate a sandwich shop in the CBD as a result. But it might be a relatively good time to be operating one in the suburbs or feeder towns (inflation might deflate that a little).
Back in around 2017, I remember looking at the local council's development plan for the city I worked in until 2021 - they had planned for office development for 100,000 more workers, and accommodation for 20,000 more people. Where were the net 80,000 extra people going to live? The residential property situation in the city was already popularly described as a crisis, and unsurprisingly, it only continued to get worse until 2020, with the only thing that's been slowing it since then is people leaving the city to work remotely.
I can’t see any reason why I’d go out to buy one for $10 instead of making one for $2-3 at home at any frequency anywhere near as often as I bought lunch when working from the office. That sandwich shop needs me to buy $10 sandwiches and I’m not going to walk past my fridge to go do that very often.