It's not just degrading coverage, Verizon no longer allows 3G device activations and is shutting down the 3G network completely on 12/31/2019 [1]. ATT is doing the same in a few years.

Interestingly, they are also no longer activating 4G devices unless they support HD Voice, so the iPhone 5s and 5c are out even though they support LTE.

[1] https://www.verizonwireless.com/support/knowledge-base-21881...