Everyone who pays for TV should be constantly watching the cost .vs. benefits curve.
If all things were equal (availability of broadband everywhere in the US) then that would be true. But (unfortunately) it isn't. YTTV could be $5 a month and it still wouldn't work for someone living in rural Missouri. That's the primary reason I hang around this forum- to remind us that while streaming may be the future, it hasn't replaced other delivery methods and won't for quite some time.
Not only that, but other delivery methods are still very effective for many. Take OTA for example. High quality picture and programming for free if you're located close enough to the towers.