FYI and from the horse's mouth, Verizon is definitely pulling the plug on CDMA.
https://www.verizonwireless.com/support/knowledge-base-218813/
Starting January 1, 2020, Verizon will no longer allow any CDMA (3G and 4G Non-HD Voice)
Notice that they are not pulling the plug so quickly.
This year, they are only disallowing new plans with CDMA devices.
If you are using one and do not change your plan then nothing will change for you.
Beginning in 2021, supposedly customer support involving these devices will suffer.
I say supposedly, because I find it very difficult to believe that any aspect of Verizon customer support could be any less than it already is.
That is why I will always do my utmost to stay as far away from Verizon as I can.
At any rate, with the timeline that they have set, the devices involved will be on their last legs anyway as the batteries powering them will be dying.
The two cellular devices that I use are on AT&T and Sprint.
The AT&T is a GSM oddball Blackberry knockoff from the era of 2G to 3G changeover.
The Sprint is an el cheapo that has both GSM and CDMA capabilities.
I have not paid any attention to AT&T's changover plans, but if it is possible I would love to have both systems on one device, from both carriers.
The AT&T is an emergency device for when travelling and I cannot get a signal from a Verizon tower.
Believe it or not, this has actually been useful in the past.
That, and the fact that I am sentimental of the number, which I have maintained since 2001.
That was back before GSM, when AT&T still used TDMA, and Verizon was using CDMA.
That is just how old CDMA technology is.