Cost of calls from landlines to mobiles, particularly from relatives abroad and/or those who simply do not use internet, are the primary reasons why we have to keep a landline, and which I will be using to hook up a Smart TV soon.
It is also necessary if you work from home and for many sourcing professional services simply having a mobile number to contact can ring alarm bells as to just what that professional status actually is. I also see a lot of posts on here where mobile users have got frustrated about the limitations of their mobiles for posting on here - and it is so much easier to use the the pc or mac.
But I certainly would be lost without a mobile now, although the increasing email/text (that are on silent) and clearing them is becoming a full time job in itself - its no wonder people seem glued to their phones these days