I read somewhere a few weeks back that a company is making SIM cards as IC chips for the "Internet of things". I can not find the article again or find anything about it on Google. Did I make this up?
This is called an e-sim or eSIM, a technology which is still not really on the market I believe, but pushed forward by IoT and giants like Apple alike. There will be SIMs in a format like DFN, possibly with support for reprogramming the carrier which is necessary for the consumer market.
Uhm a SIM card is a chip, we're just used to seeing them in a form factor which humans can "easily" place in and take out of their phone.
If you were sure you never needed to change the SIM card or your phone, you could just solder the chip from the SIM card directly into your phone.
Having a SIM chip in a small standard IC package would indeed be a good solution for devices which need a SIM card but where size and/or cost is an issue.