I dumped my landline back in 2000 when I realized that my landline provide the same service as my cellphone. Both cost about the same and unless you need to call other countries it makes sense. Cell phone charges to call other countries is ridiculous high it most cases and I think a landline would be more economical in those instances.
Let's see ... I have a landline, internet connection and TV service (FiOS) for about the same price as the cell phone service my friends have ... so yes ... I still have a landline. And no ... I'm not a Luddite ... been working in the IT field for the last 15 years and I do keep up with latest trends (and no ... twitter is not a trend but a fad).
Change the punchline to "your email address is AOL, that must come in handy when someone from 1993 contacts you" and you've got a better IT gag.
In the US mobile phones are a lot cheaper than landlines now because of competition. In the UK I imagine the government puts all kinds of roadblocks up to protect the phone line worker's unions or some such nonesense that makes replacing landlines with mobile phones only possible for the wealthy. There are lots of local mobile phone carriers here in the US that offer unlimited calling plans at around $45/month. And calling a mobile number does not incur any special charge. You should complain to someone about that over there.