GSM Sunset - Phase Out - EoL - Shut Down... Is GSM already Dead?

Hello Experts.

The GSM Sunset (or Phase Out, End of Life, Shut Down or any other term to refer to it) is no longer a possibility: it is now in the horizon, and very soon will be no longer an option.

For few years, carriers and vendors have being procrastinating this, due to several factors.

It is now time to we prepare to this new age.

Several carriers will shut down GSM this year:
USA: AT&T Dec2016
Australia: Telstra Dec2016, Optus Apr2017
Singapore: Singtel Apr2017, StarHub Apr2017, M1 Apr2017
And the list is growing…

So, i would like to have your advice, on what will be main advantages/disadvantages of this big happening?

GSM Phase Out is a reality? Or will it last for long years yet?

Any comments will be appreciate, as soon it will be a reality for everyone of us, and we need to be prepared.