MSNBC has a bit more detail:
And the reason for the release is pretty clear: the bad-mouthing was impacting the stock price.
And, let's be honest, whether the sales are upgrades or not doesn't matter.
Money is money whether it comes from a new customer or an old one.
(Hence the press release to calm the stockholders.)
If anything, upgrade sales will cascade the used models as hand-me-downs or used-hardware sales so the install base is still going to grow.
Likewise, it doesn't much matter which of the five models is getting the sales.
Big sales for the eink models?
Big sales for Fire?
It's still big bucks for Amazon and it's still bad (competitive) news for *somebody* else.