I am about to cross a generational rubicon.
I am, sometime in the next week or two, going to call up AT&T and cancel our last remaining POTS line.
This line was "under" our DSL connection, and I had it on the cheapest measured-rate service I could get, because at the time you couldn't get Naked DSL. And, at the time, we had DirecTV receivers that required a connection to a land-based phone line, and we had our alarm system and we used the number to receive faxes.
Well, within a space of about 2 months, I've managed to make all of those justifications vanish. We tossed DirecTV and bought a TiVo Premiere and Comcast cablecards; we replaced our DSL connection by moving the server off into the cloud and buying a cable modem; I've equipped the alarm with a GSM modem and an AT&T prepaid SIM card; and the fax receive capability broke when I shut the server down, and wasn't really being used for anything anyway.
So now the only RJ-11 wiring in the entire house runs between the Vonage box, the cordless phone base, and our printer (for fax sending). Everything else we do is either via cell phones or IP.
How different it was 15 years ago. In 1995 I had a dialup ISP in my home with dialup PPP connectivity to the Internet that cost 4 times what I pay now for 50/10 megabit service. I subsidized the cost of the Internet connection with the ISP business. I had, at the height of it, 5 dialup modems and a couple dozen users. From 6 copper phone lines, down to 0.