Fire tablet users will be able to access the store until the total shutoff in 2019, but that only implies to current tablets. Future devices will not have access beyond the end of May, nor will Android devices. However, all users will still be able to play apps they've already downloaded. The Amazon Underground store will continue to exist; it's just the "Actually Free" program that's disappearing.
Start hoarding while you can! It's a bit confusing, but it makes sense that Amazon would reward those using Fire devices. Android users are essentially chopped liver, and come 2019, we're all chopped liver.
We are all chopped liver.