Not necessarily - the market has priced in multiple future outcomes according to their probability, each which see a massively different valuation of pound sterling. Article 50/hard Brexit/etc. is now very likely (lower pound sterling value), but there’s still the potential of a late change to this approach or a parliament refusal of the bill (higher pound sterling value).
And of course it suits Apple to focus on the highest probability event, particularly since (unlike FX traders) they don't stand to very quickly lose large amounts of money if low probability but cannot be ruled out yet positive news for the pound happens. The worst case scenario for Apple if the pound rebounds involves people thinking their UK App Store is a bit overpriced until they revise prices again.
