But regardless of what it is called people usually know what they signed up for and when what has worked for the 5-6 years suddenly breaks ...
If a consumer ISP moved its customers from separate IPs to NAT, what do you think would break? I'm the guy who was behind a double NAT for several months without realizing it, and I can report that the only symptom I noticed was incoming call flakiness on one of my VoIP phones, and even that was easy to fix by decreasing the registration interval. The other VoIP phone worked fine in its default config. Other than the .01% of consumer customers who are mega multiplayer game weenies, what's not going to work? Actual experience as opposed to hypothetical hand waving would be preferable. I'm not saying that NAT is wonderful, but my experience, in which day to day stuff all works fine, is utterly different from the doom and disaster routinely predicted here. R's, John