Learning about prompt engineering will help, but my guess is- it'll evolve too with newer versions of GPT and it's significance could go down as we get bigger and higher dimension models.

If I'd already developed an application- I would explore ways to make it AI native app. Question I'll be asking myself would be: is there anything in my app that needs prediction, classification or generation? Will my app user gets any benefit out of it?

For example: if HN was my app,I could show more relevant articles based on my history or comments. But does end user really need it? That's answer we should dig in ourself though