Many companies are run by excel applications. Excel is great. You can customize calculations and reports just the way you want. But when using in a production environment, it's no good. Especially when you have several users trying to access at the same time. And there are many more problems. Many love and hate excel for this at the same time. Replacing excel software by customized applications is usually very expensive.. at the same time, time invested in developing the excel is thrown away. I've seen this in a lot in production planning.
My idea is to use the calculations and whatever available in the excel, but building software around it (gui etc.) . .. enough to have be user friendly and ready forproduction environments. And all this, offered as a service (SaaS), so that no investements are needed for customers.. I have seen many excels and have technical ideas how to do this. Market opportunity is huge, but the task is not easy.