Unfortunately as a consequence to Carlos Slim's quasi-monopoly on telcos, Mexico has already the highest Internet access price in the world. I'm wondering if this law is not another attempt to lock down the system.
Home broadband connections can be had for about US$20-35 per month. Reliable 4G nationwide month-to-month absolutely no contract plans with 2GB+ data can be had for US$25 or less.
They substitute only if everyone you want to call has Skype or GVoice or something. If you want to call people with phone numbers, you need voice specific service. Telmex charges Skype &c big, big interconnect fees to access the regular telephone number voice market.
It's been worth enough to make Slim the world's richest man mostly on the charges for USA-Mexico voice interconnect fees. I used to talk to my US contacts on Skype.
This isn't true. I use google voice and the GrooVe app to make and receive calls to and from land lines. They don't need GVoice; I do. And I have it.
Then again, my GV calls connect to US numbers. On examination, the Google Voice rate to call mexico is indeed ridiculously high ($0.15 / minute -- compare the $7.14 / minute my parents' land line wanted in order to connect to China [GV rate: $0.02]).
But if the use case is talking to family members on a regular basis (seems likely when the cash cow is US -> mexico calls), it shouldn't even be difficult to tell them "if you use the internet, we can all talk for free". Your family seems especially likely to be willing to make some accommodations.