You guys are worry too much.
I have been running some light simcraft with the new gear lists, and it's still by far best in slot until anything you will see until Heroic Madness. The only staff that even compares only has a marginal difference with intellect, and the proc as someone said earlier will still be very strong, and even stronger with increased gear. That 8% chance to duplicate a spell is roughly 8% extra damage, possibly a little less depending on spell it selects.
Be thankful that this is one of the few legendaries that isn't obsolete in the next tier, or that you only get it for one tier.
My prediction is that it will still be best in slot, but it wont be like the legendary daggers or anything.
You guys should worry more about our damage compared to other classes. We're still not doing so well... we're below a lot of DPS class second-level specs, which is pretty bad.