Are there any traditional grocers causing the lack of market share? If it is all discounters, super centers, and Warehouse giants, there is room for a player. A lot of people don't want to shop at Walmart, Costco, Woodmans, ect. They want convenience, high quality and value. I would never buy groceries at Wal-mart. Their stores are a nightmare of screaming kids and idiot employees. I like diet coke and Doritos as well, so WholeFoods is out. Maybe PNS needs to retreat from the poor demo areas, but high income, infill locations should be able to survive.
You obviously missed one factor. You can check out easily at Woodman's, Walmart, Walmart neighborhood markets. Something PNS gave up on years ago. Quite often I combine my shopping for non-grocery and staple items at Walmart. Most staples are priced better than PNS. I also GET TO CHECK OUT QUICKLY as their checkouts are manned. Meat? Well, cheaper but I do not get anything but tongue, the Smithfield marinated pork for the pressure cooker, and large hams when on sale (doesn't take much to turn into a honey baked clone with a blowtorch). The visit to a Metro this week was not a great check out experience either. If they weren't the only local importer for my favorite cheese I would not be going in despite them being close. Even the Pig was cheaper on fresh fruit/veggies, and that is saying something.
On a well known news/humor aggregator I hang out on, there was a comment about PNS diverting cash to Chicago. There were more than a few comments of "that's why they went downhill/suck/don't shop there anymore" from quite a wide area. The sooner someone picks up PNS and continues their slide to a "save-on" quality the better.