I'm not a gambler, but...
I'd be prepared to wager a couple of pounds (or Dollars) that we'll never see an iTablet.
All Apple's products are replacements for naff predecessors. Desktops, laptops, music players, phones, they all existed but were a bit naff. However, what they all had in common was potential - they filled a very real need.
But a tablet? There is no potential. It's a solution looking for a problem. If you try to think how you might improve a tablet through, you end up designing a laptop or a net-book or a large screen iPod.
My money's on either a small screen MacBook Air, or a larger screen iPod Touch.