The Big East has survived raiding. Half our fanbase wishes we ended up there.
And really, aren't most conferences @ the mercy of a few schools? Imagine what happens if the Ohio States of the world get tired of paying Northwestern's way. Substitute 'Bama and Vanderbilt or USC and Washington State if you like. The Big 12 economic model might be more sustainable long term if this TV deal comes out good.
The Big East did and it's a shell of its former self. The SWC didn't survive raiding though.
You're right about being at the mercy of big schools, but those small schools like Northwestern have history to rely on. OSU would never do that to Northwestern because they view each other as brothers or a spouse. The Big 12 is like a one night stand with some bar skank.