I haven't studied that so I'd refer you to the PBO on that front.
It wouldn't surprise me if TFSA has cannibalized RRSP savings. I think for wealthy younger Canadians in particular, it makes a lot more sense to invest in a TFSA, because upon retirement, you gain full access to the guaranteed income supplement and old age security because TFSA withdrawals don't count as income the way RRSP withdrawals do. One of my longer-term concerns, besides the cost—although there's a study that...more extensively than I have—is we will easily have TFSA millionaires in 20 years who would access the full benefit values of the guaranteed income supplement.