I don't think this is likely to be a real issue in the grand scheme of things.

SaaS customers pay for a product that provides a workflow and a structure for solving their problem without them having to think too hard about a solution. They are outsourcing the problem-solving work, not just the programming effort.

If you must worry, you should be thinking about the new wave of competitors and copycats using LLMs to replace their programming effort. They are the ones coming to eat your lunch if you don't have a defensible market position.