The app has been unpublished from Google Play. New people will not be able to download the app but existing users can download the app from the My Apps section of Google Play. The app has not been abandoned and will continue to work for the foreseeable future. This is the same case with my other app Flamingo that was unpublished many months ago but has since had a lot of changes to account for Twitter's breaking API changes in August (thanks, Twitter).
It's worth pointing out that apps don't last forever. Weather Timeline has been the result of thousands of hours of work over many years (since Android 4.4). It's been cloned several times, been pirated and almost been sued (a company thought they patented the concept of a weather app). Most users have been using the app everyday since 2014/2015 for half the price of a cup of coffee (of which Google takes 30%).
As downloads dwindle, if the app was not unpublished now then it would get to a point where I'd have to introduce an in-app subscription or the app would break for new users who had just downloaded the app. That didn't seem fair so I unpublished it now so that everyone could enjoy the app. I did the same with Flamingo where I unpublished it slightly before it hit the token limit so existing users could add their extra accounts.
It's not easy being an indie developer. For a project as big as Weather Timeline it takes countless sleepless nights trying to keep everyone happy. I hope you understand that this decision was not an easy one.