Not as quickly as you think. China Telecom for example still has 250 million customers on their CDMA/LTE network. China won't be phasing out their 2G networks anytime soon, their 3G networks will go first (W-CDMA and especially TD-SCDMA). CDMA's 3G and 2G are compatible standards so will maintain that as well. Between them and Sprint, CDMA will survive, but it will be niche.
It's getting worse than ever. I don't see so much lack of B41 as I see unusable B41. -85 B41 signal that's as usable as communicating with Antarctica from Oxford using smoke signals (have to manually defeat B41), dropping calls on handoffs with good CDMA signal, transitions between LTE bands are accompanied by up to 10 seconds of "No Service", similar periods of "No Service" during handoffs between LTE sites even with good signal. I can reproduce that behavior on the devices, and the dropped calls on four.
Still, the only responses I get from Sprint are basically "Get lost" answers.
I feel like some people are reading things into this that aren't there. VoLTE is going to be opt-in and CDMA isn't going anywhere for a long time. All of the other 3 nationwide carriers still have some sort of legacy voice solution still available and they've had VoLTE launched for a while now.
For those of you in areas where LTE isn't there yet, don't opt in. For those of us who are in areas where LTE site density is good enough, we'll have no issues.
That's the thing, it's the opposite where I visit. The places I visit could have had volte a long time ago. Also, the other 3 players didn't have the same level of 3G voice Sprint had unfortunately, especially Tmobile, they didn't have as good of voice coverage to match.