Yes, this is irritating. We are replacing the WU link with a yet-to-be-decided system (smartcitizen.com looks really good) Aries also looks good.
What we are doing right now (as we speak) is adding support to GWP and OurWeather with the Blynk app. Not a backend database, but it solves part of the "I want to see my data and share it" issue.
Love that you are adding support for Blynk. Smartcitzen looks like a great option too. Smartcitzen is well-funded, and committed to open sorce whatever. Have you considered creating a wordpress plug-in? The advantage of word press is that it is not going anywhere, offers a wide range of Pokémon option that are free to reasonably affordable.
What's the latest on this? I noticed that while WU has apparently discontinued the "old" API, it appears they also have a new one. I bought an Ambient Weather station for my GF's house, and it connects to WU with no problem - I can see the data being updated. Maybe they just want us to upgrade to a new API?