Just so that you know: API keys for PWS non-commercial users are going to continue to allow the PWS owner access to all their data. There may be another gating mechanism (rather than keys) in the future, but there is no plan to discontinue PWS access.
The latest information may be found on https://apicommunity.wunderground.com/weatherapi
Lack of a key should not limit anyone from adding a new PWS as well. See https://www.wunderground.com/personal-weather-station/signup?new=1
Weather Underground API customer service