The iPad was selling 170,000 units a day in Q4. I expect that number will be exceeded in Q1...
Eventually you get to a point where the market is saturated and those initial spikes fall off dramatically. There is a finite amount of consumers for a $650 tablet that duplicates functionality found in PC's and Smartphones.
The iPad is only 2 years old, smashed records for volume and revenue in the +$500 computing sector, and the fact is that 80% of iPad buyers aren't flipping an expensive item like that in under 24 months. If it weren't for the speed boost and the retina display, I'd have happily stuck with my iPad 1 simply because it was meeting my expectations and there wouldn't have been a need to upgrade.
The market for the The New iPad looks like this:
30% = iPad 1 upgraders
65% = New tablet buyers and/or second-in-household tablet buyers (ie for the wife)
5% = iPad 2 upgraders
Point being that the largest current existing market of buyers are very satisfied with their 2010 or 2011 iPad's and aren't thinking of plunking down another $650 for something that's working well for them.
BJ