I'm considering this idea from the standpoint of where Lancaster is in terms of angling proximity to quality waters as well as the general SE PA demographic in terms of urbanization and average income and the like. Based on these factors, I have a hard time visualizing a destination-type independent fly shop succeeding based on the older-style fishing gear, accessories and tying materials business model.
When we have lived in proximity to large metropolitan areas (and really, Amish and all that aside, Lancaster is pretty much on the western edge of the great East Coast Megablob and as such is an urban area), the shops that have done well and stayed afloat almost always were in both of the following businesses: 1) Travel Agents/Trip Facilitators for exotic fishing destinations like Costa Rica, etc. and 2) in addition to fishing gear, also in a line of quality merchandise that drew a customer stream of non-anglers. This could be something like Vasque or Danner hiking boots, Pendleton, North Face or some other high end clothing or some other merchandise of high quality that has an outdoorsy connection, but is not about fishing.
I'm pretty sure that this formula is how a lot of the Orvis shops in the bigger metro areas stay afloat. The margins on clothing and footwear are pretty high, usually significantly higher than on rods and tying materials, etc. And as I sort of said, the customer stream is broadened. It is a bit of a dilemma for a new shop setting up in these sorts of areas. The disposable income to make it go is usually present, but the specific interest in fly fishing is usually not potent enough to successfully tap into the revenue stream.
Good Luck~!