AT&T was a first mover in this respect. The US operator's decision to phase out 2G services through the end of 2016 was completely rational from a business perspective.
I think you'll find that Verizon migrated to 3G before the others. To be precise, Bell Atlantic, in those days. Mainly because they chose CDMA when going from AMPS to 2G, and narrowband CDMA, used for 2G, is band-compatible with the newer wideband CDMA variant, cdma2000. So when Bell Atlantic and then Verizon introduced 3G, their entire digital spectrum could be W-CDMA without leaving the 2G phones high and dry.
The auto companies migrated from AMPS to 3G directly, for telematics apps, I believe. I'm curious still to see what happens if auto companies now make a move to 4G. Will they repeat their dropped-like-a-hot-potato AMPS cars, for telematics? Or will they offer an upgrade option (uh, I mean aside from "feel free to browse our showrooms for a new car")?
Cellular m2m has been going on for some years. It will stay as a niche market. Nobody wants to use them unless there's no other choices. License fees is too high. Priority is not guaranteed, in particular, in the busy hours of holiday seasons. It may be rising but in a small scale.
What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.