I lived for about a year without cable television to reduce costs as well. Football is one of the tougher sports to find online, but if you do a google search on live streaming new york jets (or whatever your team is) game or something along the lines of that you can usually find your way to a site that has the game on. I kept coming across this one site, I can't remember the name of it, but it was all in Spanish so I would have to use Google Chrome to translate it for me. But Sunday night football NBC actually streams live on the internet, and Monday Night football is on ESPN and you can pay for ESPN 360 and watch it on that, or I know some service providers give you free access to ESPN360, such as Verizon Fios.
As for watching tv shows, I watch most of my tv online now, honestly Google is just the way to go for it, google "watch sons of anarchy season 4 online" and I'm sure you'll find a link to a site that is streaming the newest sons of anarchy. Hulu.com or even now a lot of stations post their shows online as well just with commercials.
All in all, it's doable, but if you're a true football fan and don't have a local bar you can go and spend a few dollars at and watch the games, then I'd say wait til football season is over and then get rid of cable.