Your changes made in the last ten years would still be your exclusive monopoly so your revenue would probably not change much if you really have been continously developing it.

But even if this would destroy your business model, that doesn't mean it would not be a good idea for society as a whole. Business models become obsolete all the time. If there is enough demand for your software, you will be able to fund the development of it even without might-as-well-be-perpetual exclusive control.