This first launch is going to be the most scrutinized & criticized Mac Apple has launched in years. Apple knows this and they are going to put a beefy CPU in their new machine to silence the critics. If they can't beat Intel performance at launch, what are the chances they are going to be able to beat them a year down the line?

And since it would be quite weird to have the smaller MacBook be the better/ faster iOS development machine, it seems like the 16" is pretty likely. Maybe not launch day, but within the first few months at the latest.

They might keep the Intel based MacBook around and sell them at the same time, but I doubt it will be the only 16" MacBook they sell for long. It just doesn't make any sense.