eSIM is easy. There is no physical card, only software verification through scanning a QRCode from a provider. Phones can theoretically have as many phone numbers as possible. My iPhone has two eSIMs, one for Wind Tre in Italy and one for AT&T in America. However, when I switch phones, I need to call AT&T to change, and I must go to a Wind Tre store and pay €15 to transfer my phone number to a new phone. Not as seamless as companies want you to believe.
In the past, I would buy a regular SIM card when traveling to a foreign land, so I could use the internet and have a local phone number without paying roaming fees. This is not necessary for the EU anymore, but outside the EU, it is still required. When arriving in a foreign country in the baggage reclaim area are companies selling SIM cards for a few Euro in local currency. I have never seen any of them selling an eSIM.
eSIM is not universal. Many big companies around the world use eSIM, but the smaller companies, the ones at the airports, usually only use regular SIM cards. This makes a SIM tray very important to have in a phone. Apple has decided to remove the SIM tray in the iPhone 14 models in the United States only. This decision has nothing to do with making something better but saving costs. Many of the smaller companies in the US only support a regular SIM card, which may make consumers think before upgrading their phones and will make it harder for those who used to buy SIM cards in foreign countries.
Will this become the new norm? I don’t think so. The EU would probably block a move to remove the SIM tray as an anti-consumer for the near future. This would only be allowed if all carriers, or most carriers, support eSIM, which is not the case currently in the EU and other parts of the world. Apple does have a more significant share of the market in the US, while they trail Android a bit in the EU.