When they really need to. But they'll fight it hard! Apple's business model is to lock everything down -- very closed indeed. This does not align with the goals of bitcoin, at least, how I perceive them.
tl;dr Apple = closed. BTC = open.
I dont think so, if apple will accept bitcoin right now. Because the value of bitcoin is very low. And if apple will accept bitcoin maybe its more processing that happen. Because apple is very rich and they dont need to take a risk of their company.