As niche SaaS provider, I'm trying to avoid succumbing to the same fate. The product I built carefully for years would now be within the reach of a senior dev with a couple focused weeks -- if they knew all the requirements. To avoid being overtaken, I'm working to increase my customer's requirements -- getting them hooked on new reports and features I never had time to build before LLMs could do it for me. This makes it less likely for a competitor to be able to afford to quickly replace me.
At the same time, I have no idea what the cost of LLMs usage will be in the future. So I'm working to ensure the architecture stays clean and maintainable for humans in case this kind of tooling becomes untenable.