I would buy a feature phone today, preferably something eink, if it was painless to switch my SIM between it and my smart phone. Having to take the SIM out of one, put it in the other, then turn on the phone is not painless and they do not design the little draws to support thousands of open/closes against the contacts to read the SIM.

There are times I want the smart phone to have the SIM because I will want or need the extra functionality and if you just make the feature phone do everything then its just morphed into a smart phone with extra steps. I want the feature phone to be basic as I can get away with.

That said, I really want google wallet or similar that I can share between the two phones for my passes and tickets, audio streaming support, and maps.

I cannot replace my smart phone, rather than supplement, with any feature phone because I use it for such a wide range of things. I can ssh from it to my home devices, I can manage my bank accounts, it tracks my health, it provides video and audio streaming on and offline, I can read and write documents/spreadsheets, plus anything you can do via a web browser.