I guess they're thinking ahead in terms of economy of scale, they won't want to still be producing A8s or A9s just for a single line of computers in 2-3 years, and if they just leave the A10 in there they don't have to worry about swapping it with all the implicit extra work every time they refresh the other internals. It is interesting it's a whole A10 though, I believe the M10 is what drives hey Siri, or is that just what listens out for the command with the actual chip firing up once it's confirmed you're giving it instructions?Hey Siri has worked since the A8, I don’t think it has an A10 just for this feature - there’s something more to this.