The store was in read-only mode to prep for the new iPhones so the sales loss is already accounted for.

As a side note (and speculation), as compared with other online stores, I don't think the Apple store has the same risks as the other stores (the fact you don't buy the Mac directly from Apple doesn't really affect their revenue).

I don't think the impact is that severe. If you're planning on buying an Apple, and you visit apple.com and it's not up, then you wait until it's back up.

Consistent downtime can damage a brand, but this is just a hiccup.