Will I have a degraded roaming experience with the AT&T iPhone 7? I read that the AT&amp;T version of the iPhone 7 does not support CDMA.

I am trying to understand what that means for me if I upgrade.  I get that it means that I will not be able to switch to Verizon and keep using my same iPhone.

But I don't know if it means that I will have other issues while using my iPhone 7.

For example, as I understand it, if I go to a place where AT&amp;T has poor coverage, then my phone roams and gets coverage from other carriers.  (At least this is how it used to be.)

Do I lose this ability if I get an AT&amp;T iPhone 7?  Are there any other drawbacks to the intel chip in the iPhone 7?
CDMA is primarily used in the US. Nearly everywhere else uses GSM. If you are an AT&amp;T customer, you will not roam onto a CDMA network. AT&amp;T sells GSM phones, so their roaming partners would naturally by-and-large need to be GSM carriers as well.

Wikipedia has a list of carriers around the world with active CDMA networks and it's extremely short. Even Verizon (US) will be shutting down its CDMA network by the end of 2019.