It's kind of dangerous NOT to have a landline and as an ex cop and ex 911 dispatcher, let me tell you why:
In the event there was some kind of emergency that you could not speak or speak well enough to tell the 911 dispatcher where you lived (choking, intruder, altercation,etc.) you would pretty much be screwed. On a landline, your address pops up on their computers automatically, so even before you can confirm your address, that dispatcher will have someone already on the way to your house. However, with a cell phone, you need to be able to tell them where you are because no address will automatically pop up. In the event that emergency services needs to use the GPS feature in your phone to find you, it's a time consuming process. So especially for examples like the ones above, it's actually pretty dangerous not to have a landline. With a landline though, even if you dial 911 and hangup, when they call you back if you don't answer, again, they WILL send someone out to check on you. When this happens with a cell phone, they try to call back and if you don't answer, they just assume it was a mis-dial. A lot of people probably don't think of things like that when considering whether or not to keep their landline, but hopefully you all will now!