"Grandfathered" situations are subject to change. If a local municipality deems something a hazard or health issue, they can and will remove the "grandfather clause". Also, if the local planning rezones your area, the rules can change.

For example, if you own a business in an area zoned residential with light commercial priveleges, then the city comes in and zones it completely commercial, you will be forced to update the property to the standards set by the new zone. Even things that would seem minor, such as the minimum number of parking spaces may have to be adjusted.

The city is not obligated to pay for those updates. Their justification is "your property value increased as a result of the new zoning". In their eyes, they are doing you a favor.

America is a free country governed by laws, and government regulations to protect the public. The privilege of having a business requires adhering to local ordinances, which invaribly will cost you money to comply with. For instance, in our community, a no smoking ordinance was just passed for bars and restaurants and all public buildings. It does not matter how long someone has been in business, or how a business owner feels about this intrusion upon their property rights, etc. The ordinance must be complied with, or a business will find themselves paying some serious fines and maybe arrested as well. Using this as an example, times change and government regulations change. Businesses must adapt or close or hire a lawyer and fight city hall. You will probably be wise to make the changes you are being requested to do, finding a new location that already is up to curent regulations, or getting a lawyer and fighting it. But which option will cost you the least in the long run? Keeping a small business open is no picnic. My hat is off to you for being in business for over 5 years!!