A couple things to think about
1) We will likely be changing the format of the API slightly. This will impact owners if you use third party libraries to get your data
2) Some of the features won't continue to be available, especially initially. We'll have a list of features we plan to persist and some documentation soon. We'll listen to your feedback and do the best we can to serve your needs.
I want to thank those of you who stick with us and continue to support Weather Underground. I know we do some things that seem maddening, and seem like they are ruining the product you love. Rest assured many of us are working to make things better and while some things get worse on occasion, they are all in service of supportability and sustainability. Without these changes, many features of WU would already be dead.