If you think the NSA is going to sprout (say) a drug enforcement arm, why are you so worried about telephony metadata? Clearly, there's no law constraining NSA at all; were I you, I'd be more concerned about them disappearing me for making public arguments against them.
I am more concerned about them disappearing people for making public arguments against them, although I suspect I would be nowhere near significant enough for anyone to notice.
I'm always interested in people who think like this. If the NSA --- or for that matter any other part of the USG --- was "disappearing" people, what does it matter what FISA says, or how much metadata they're collecting? Clearly no law we have has any impact on them at all.
