Apple is using an Intel only modem and it even confirmed that it will confirm Gigabit LTE. It could have supported it last year with the Qualcomm Snapdragon modem based phones in CDMA networks in US, China or Japan. Well, Apple doesn’t want to talk about that.
Nevertheless, people who love the iPhone now have an eSIM if you are on Thrufone, Verizon, T-Mobile, EE (UK), AT&T, Jio, AiTel, Bell, Vodafone, GigSKY and Deutsche Telekom. You will be able to add the details of your SIM card to your phone and it will work, hooray, no physical card with these carriers who support it.
In China, there will be a real dual SIM solution as China doesn’t play dual SIM. So if your carrier is not listed, you will have to import the phone from China to get the real dual SIM thing. It has a dual standby, something that Chinese companies had many years ago. Qualcomm solutions have it. MediaTek powered phones have it. Samsung has it. Huawei has it. So Apple is clearly last to the game with dual-SIM/dual-standby.
Gigabit LTE is something that everyone but MediaTek has had from the list above and Qualcomm can even support 2Gbps with its latest modem. Yes, that is two times faster on Gigabit LTE networks compared to the latest iPhone and this will ship - at the latest - with phones in early 2019. Don’t even talk about 5G. That will massacre the iPhone XS modem performance next year.
The Intel XMM 7560 is definitely a catch up with two year old modems from Qualcomm and lags behind the speeds of Exynos modems from Samsung and even the Huawei Kirin 980 modem speeds.