The offer of $99/mo unlimited calling plans means the beginning of the end for landlines.
Why have a landline now that you can talk all time, at any time of day, everywhere [in the US] you go? There is no reason. Depending on your current cell plan and landline plan, you might pay a slight premium for the new $99 plan. However, the average consumer might decide that the premium is worthwhile for the gain in mobility.
Once people start to add up their phone costs, they might find that $99 is not too bad.