Twenty years ago the papers were hawking a phone number shortage scare. Actually, this went on for most of the 1990s. The first part of the problem was resolved, if I remember correctly, by allowing more than 1s and 0s as the center number in the area code. Suddenly we could have more numbers because 305 area (Miami/Ft Lauderdale) could now split to include 954. Even 800 numbers could also be 888.
But even with this change the numbers were disappearing faster then they could be created. Phone numbers were becoming cheaper so families were adding more lines. Then faxing became popular so lines were dedicated to fax machines. Then the Internet came about and people wanted dedicated phone lines for accessing the web. And finally cell phones required another new number.
Then sometime in the early 2000s the trend reversed and the papers stopped talking about it. 
Cell phones first replaced multi-landline households and then started eliminating landlines all-together.  Fax machines, too, started to go away as scanners became cheap and built into every printer. No need to fax when scanning and emailing was just as easy. Finally DSL, cable modems and FiOS replaced dial-up modems and those already had dedicated “lines” so the extra Internet line could be eliminated. So we are back where we started — or at least close to it — with people having a single phone number aimed at their cell phones. 
I’m going to think about this example every time the TV or news calls for something being a total catastrophe if we don’t do something. Yes, sometimes intervention is required. GM needed government help in 2008 or millions of jobs were going to go away, making a tough economic climate even more so. Yes, if we don’t do something about Medicare it will bankrupt my generation. But many of the small issues, the ones the papers and newscasters love to crow about as if it is the edge of the world, are resolved “on their own,” whether because the problem ceases to be a problem or whether innovation resolves the issue.
The trick, of course, is recognizing the difference and acting (or not acting) accordingly.
 The only reason I even thought about this is because I am re-reading Microserfs by Douglas Coupland, my all-time favorite book as a 20 year old.
 If I built a house today I’m not certain I’d even string phone line through the house. Why bother? I’d rather have terabit ethernet lines.
 Yes, I’m ignoring stuff like Google Voice that technically is an extra phone number per person but let’s face it, that’s pretty niche stuff right now. And yes the original way was one line per household but expanding to more than 1s and 0s as the center area code number solved that problem, which in and of itself was a relic of the rotary dial system that was fixed with technology in the 1960s.