I worked for Nokia Networks (the cell tower/voice switching side) for 6 years. In Europe, turning off 2G GSM would be like turning off landlines. It’s used in so many fields (industry, science, metering, even emergency) that it will run up to 2020s and even then 1.8Ghz will still work (you will just be unable to buy new 2G sim cards).
Nokia 3310s were also not “world phones”. Hardly any european-sold phone would roam properly in pre-iPhone USA and vice versa. However, these feature phones have a modular radio unit, so it’s not fixed in stone - it’s mostly a matter of price and market.
