Two things on this.
First, a securities firm "believes" this. I'm assuming it's not based on nothing, but still, this is not coming from Apple at all yet. But let's say it's correct...
...then second, we're talking about a 1m cut and 2m increase in a bucket of 80-100m units. This is nothing like what Samsung did by abandoning the line altogether. These are pretty typical supply chain / inventory adjustments. It's obviously not a "positive" for the Air, and not a surprise for the others, but it's not some sort of nail in the coffin either.