HDTV you can get with an antenna, for free. You may get ABC, NBC, CBS, CW, PBS, IonTV, and a host of other smaller networks, depending on your location.
Discovery,Nat Geo,History Channel, and ESPN, you can't get with an antenna. Depending on who your internet provider is, you may be able to get ESPN 3 on a computer or set-top box, like Roku, or one of the game machines (Xbox, PS3). Some of the content from the other channels is available online on Netflix, or HULU, but you'll have to wait for some of it to become available.
Cutting the cord involves choices and sacrifice. You give up the ease of switching with a press of a button to hundreds of channels. What you gain is money in your pocket, higher quality TV picture with an antenna, and the freedom to choose what you want to watch and when, if you watch on the internet.
If you're tired of the cable bill always going up, and paying rental fees for a set top box every month for each TV, you can save money. BIG money. Since I cut the cord, I've saved over $3000. The savings paid for my 52" LCD TV, and now all I pay for is for Netflix - $8 a month. So if you can give up a little to gain a lot, and you're still interested, respond to this thread and let us know. We'll start you down the path to cutting the cord.