It would depend how it's done IMO. Taking Doncaster as an example, if they applied for and were granted a franchise in a new franchise-based league and continued playing as Doncaster Knights at Castle Park, then I'd agree with you. Hopefully, in order to be granted a franchise, teams would have to demonstrate how this would grow their business. For example changing their name to the Yorkshire Puddings, playing at different grounds around the county and working to improve links with lower-tier teams in the county.
Cornish Pirates are a decent case study in doing this within the English game. Until some point in the early/mid 2000s, they were Penzance/Newlyn RFC and played their matches at the Mennaye Field in Penzance. They then rebranded as Cornish Pirates and moved their home games to Truro (capital of Cornwall, centralish population wise) and then the Camborne (a rugby town within Cornwall's rugby heartland). Following a fallout with their landlords in Camborne, they moved back to Penzance (geographically isolated at the extreme of the peninsula) and their attendance has declined to (less than?) half of the averages they were hitting. I'm sure there's more factors than pure geography at play, but it is at least an indication of what can be achieved by embracing a franchise approach.