I have an app that I've now installed on 3 different cell phones as I've upgraded them over the years. It was given to me by the writer for feedback and comments, but then their professional life became such that they never finalized the app.

Thing is, I use the app a lot. It's very unique and has no competition because it fills an extremely narrow niche. Side loading it has worked for several years on several increasingly newer phones.

I'm not sure if that's exactly what your question is about, but I think it might be.

When we reach 128-bit architecture, that app will fail. But I don't expect that to happen any time soon.