Building a business on Part 15 spectrum has risks; you have no priority over anyone else.
Coordination with other users (i.e., Parts 15, 74, 90, and 101) can extend the life of a network.
A properly engineered and designed network will live longer than one that isn't properly designed. However, a well-built network may still have a limited lifetime if there is an increase in noise or interference from other users.
Other users may try to stifle 802.11 communication by suggesting changes to the FCC Rules and Regulations. A well-coordinated effort that tracks and responds to proposed rules detrimental to Part 15 users is needed. WISP organizations or the loosely coordinated networks of FreeNetworks.org might be able to provide some assistance in this area.