The story in Slate about the death of the landline presents "partial truth" in my view as it picks up a theme that anyone who has had statistics in college quickly learns.
The game we learned was called "how to lie with statistics" which really means telling the truth, but using the stats in such a way as to obfuscate the real facts that are also in evidence. You simply leave them out or use the numbers in the best way to only portray your point.
Yes, Gracie, telco landlines are dropping. That's true and we all know that. The author even goes so far to point out the rest of the story, but leaves a lot out as well:
The growth and convenience of wireless have played a role, and so, too, have the rise in broadband Internet access and the availability of phone service from cable companies and outfits such as Vonage and Skype.
I would contend that a significant portion of the perceived defections really do remain landline user, but are instead landline replacement to another form of landline, not land line abandonment to wireless as a cursory read of the story would lead one to believe.
Cable MSOs led triple plays and the VoIP operators like Vonage, AT&T CallVantage, Broadvoice, Earthlink's TrueVoice and others are where the landline crowd has shifted to, as well as to VoIP services like Verizon's VoiceWing. Those numbers are not factored into the story, and make up what I call Voice 1.5.
Voice 1.0---> Telco/PSTN Supplied Telephony-via RG-11 and billed by the Local Exchange Carrier (LEC)
Voice 1.5---> Digital or VoIP Based Delivery of PSTN Like Telephony Services--only difference--the wire (Ethernet) and the bill comes from a usually different source
Voice 2.0---> IP Based Delivery of Advanced Voice Services with more features than the LEC offers
Thus my contention is that Voice 1.5 and Voice 2.0 customers in the home are using landlines and should be counted in the total, and additionally that the cable companies are really the same as telcos in many ways.
Update-->It seems Telegeography's Stephan Beckert agrees with me. He sent this slide and a note earlier today.
Here's an illustration of the point you make in your posting about the Slate story on the decline of landlines.
The big 4 ILECs lost 2.5 million switched lines in Q1 2008 (28,000 lines/day). VoIP service providers gained 1.4 million subs. Thus the actual decline in "telephone" users was more like 1.1 million, rather than 2.5 million (and a surprisingly large number of those disconnections are still due to secondary lines)
Of course, that doesn't change the fact that the ILECs are losing fixed lines in a hurry.