Realistically, people who won't spend money to upgrade their phones aren't going to spend money on a subscription either. A different equitable solution is to make the app free but only support recent OSes; people running older OSes can use old APKs.
I’ve no way to upgrade iOS beyond 11 and miss the stock software and more. Video editing currently not possible with stock app, nor SoundCloud. No OTA upgrade nor iTunes, until I have clean cheap power and strong Internet access. Used to get it at libraries until March. Had Android, liked APK distro, glad it still works. Very cool that the store offers it, but also that there are alt stores.
Because the money earned vs old devices probably isn't worth it. At some point you have to cut support on old stuff unless there is some financial pay off or you're retired and want a hobby to keep you busy.
