The reason why arts folk uses mac are that back in the CISC vs RISC days, Macs are better for graphics. And then the CISC took over because it's evolving at a faster pace, so hence Apple dropped the RISC. But 25 years of graphic superiority reputation isn't going away even if they have lost that advantage for the better part of this decade.
If Adobe drops Apple support, people will have to switch. Good luck using iPhoto at the professional level.