I don't think it's going to happen. I think these clubs are angry at UEFA for their proposed CL changes and are using this as a bargaining chip. They must know the incredible risk they're taking from both their domestic league and FIFA at large; either they think they can actually do this (which seems unlikely, given the power domestic competitions and FIFA hold over them) or they're posturing to force UEFA to change the CL into something else.
I think the second option is more likely, especially given the universal condemnation every club has gotten from its fans and supporters clubs. That said, I could very well be wrong given the resignation of the Juventus guy from his boards yesterday.
I sure as fuck hope it's not going to happen, it will destroy domestic football permanently. I'm choosing to believe it's a bargaining tactic.