I think that having Bitcoin is still useful even with an user-friendly XMR - BTC atomic swap system existing. There are just so many people who link privacy to crime. They would probably never like the idea of Monero and automatically think of criminals when hearing about it. Atomic swaps come into help here: you can pay with BTC at a XMR-accepting store and you can pay wkth XMR at a BTC-accepting store. You can use swaps for trustless trading. You can use them to trigger from privacy to public and back.

The idea of having privacy as a default in BTC is good for us, privacy advocates, but you can only imagine how much oppression there would instantly be from the governments. They love Bitcoin currently because they have Chainalysis and a lot of people who don't give a damn about their own privacy. It's the paradise of surveillance right now. Should we get default privacy with BTC, things would change drastically. I bet.

Also, living the life without a smartphone is very possible. In fact, living without one is so much better. Ditch your smartphone for a week and see for yourself. You can always have a smartphone without a SIM card in it that you only use for WhatsApp or so and never take it with you outside.