We have one here. We live very rural, and the mobile signal is shockingly bad sometimes. I would never voluntarily get rid of my landline.
Someone said to me a few months back, that BT were thinking of dispensing with everyones landline, and making everyone have their landline phone through the internet (V.O.I.P.) I think it is.)
I bloody hope this is not true.
Especially as I know someone whose employer ditched the landline 2 months back, and got 'voip,' and their lines haven't worked properly since. Very few people can get through, and they have times when they can't dial out. 2 months on, and they are still struggling. They are losing business because of it!
Also, what if someone has no internet?
I'm sure there are quite a few people who don't have it! Especially the elderly. And I reckon they rely on the phone (landline) more than anyone else!!! They would also be less likely to have a mobile phone as well.
Also,as has been said, some people need landline for the internet. (You need it with Plusnet for sure!)