Chinese carriers claim dual-SIM iPhones are a sure thing
Apple is indeed planning to ship at least one dual-SIM iPhone this year, Facebook posts by two Chinese wireless carriers suggest.

A graphic from China Telecom explicitly depicts an iPhone X-like device with twin card slots, GSM Arena noted on Monday. A separate image from China Mobile is less direct, but still shows an apple with two SIM cards embedded in it.
Dual-SIM phones are rare in the U.S., but can be particularly useful in places like Europe and southeast Asia, where travelers are frequently crossing borders and may want to avoid constantly swapping out SIM cards.

Rumors have regularly pointed to some form of dual-SIM support in this fall's iPhones, but they've also been inconsistent as to which models. Some have pointed to the 6.1-inch LCD "iPhone Xc", but the technology could also -- or alternately -- come to the 5.8-inch OLED "iPhone XS" and/or the 6.5-inch "XS Plus," sometimes referred to as the "XS Max."
Apple is slated to reveal the new iPhones at an event this Wednesday, which will start at 10 a.m. Pacific time. The company should also announce updated iPad Pros, an Apple Watch "Series 4" with a bigger display, and more.

A graphic from China Telecom explicitly depicts an iPhone X-like device with twin card slots, GSM Arena noted on Monday. A separate image from China Mobile is less direct, but still shows an apple with two SIM cards embedded in it.
Dual-SIM phones are rare in the U.S., but can be particularly useful in places like Europe and southeast Asia, where travelers are frequently crossing borders and may want to avoid constantly swapping out SIM cards.

Rumors have regularly pointed to some form of dual-SIM support in this fall's iPhones, but they've also been inconsistent as to which models. Some have pointed to the 6.1-inch LCD "iPhone Xc", but the technology could also -- or alternately -- come to the 5.8-inch OLED "iPhone XS" and/or the 6.5-inch "XS Plus," sometimes referred to as the "XS Max."
Apple is slated to reveal the new iPhones at an event this Wednesday, which will start at 10 a.m. Pacific time. The company should also announce updated iPad Pros, an Apple Watch "Series 4" with a bigger display, and more.
Comments
I still think it is convenient while traveling because unlike the US there are very few official carrier stores in the smaller countries. However, there are plenty of little mom and pop stores all over the place that can sell you a sim and a prepaid minutes card. With a sim you don't need to program anything unlike the theoretical sim-less phone. You just pop it in and go. Even the housekeeper in the hotel can help you with that. She'll just take off her earring and pop open the sim drawer. Pretty much all the locals are used to that method. Paperclips are not in wide usage in the rest of the world like they are in the US so if you travel abroad you should consider bringing your own.
Dual SIMs are popular for some kinds of users and especially if you want your private and work lines on the same physical phone.
Carry on Project Fear though.