I've never had a landline (that was my own - that i paid for). I grew up with one, but when i went to college i eventually got a cell phone and never looked back - and don't really see a reason to. 

Now, that said, landlines probably will never die out totally, but for personal use the cell will eventually become ubiquitous. Landlines may go all digital (ip based) as cell has, but to me a landline only means that it's hardwired (not mobile). My work phone, for instance, is one of those fancy (for the 90's) phones with features and park pickup etc and i consider that a landline. Basically a landline is for a location and a cell will be for a person. 

I tend to prefer the use of the term mobile phone (or mobile for short) instead of the 'cell' terminology. Using an adjective that is too technical (cell) instead of a more meaningful one (mobile) muddies the waters and gets us into these semantic rat-holes.