Skyline in the full line up, when?

Just to correct your initial mistake, the 21.5 inch iMac only got the Broadwell chips because the ones with the better graphics cards (IRIS PRO 6200 in broadwells case) are not available for skylake chips yet. The 27 inch got skylake because the worse integrated graphics don't matter when you have dedicated graphics cards to take up the slack when needed.

To answer your question when Intel release all the appropriate chips, to give you some idea the Core M in the macbook due for release before christmas and the ones for the rMBP's are due for release early 2016.

Unfortunately for you I don't personally think the air will ever be updated again I think it will be kept as a legacy product for a couple of years and be replaced by the macbook, much like happened when the rMBP replaced the MBP.

 

Skylake M before christmas last I heard so new macbooks maybe just after.

The surface book laptop convertable thingy has skylake 15W chips (skylake U or Y??) so no fanless design or any of that jazz. The surface pro has the same chips.

Mac pro?? You mean the trashcan desktop?? Bit of a departure on the conversation but these use Xeon processors which tend to be at least 1 architecture behind the consumer chips so broadwell Xeons were released a couple of months ago but Skylake Xeons have been announced and Apple could be waiting for those.

 

Don't count on a second USB port for the rev. B Macbook. And Skylake Y is available now and released by some PC manufacturers, but not all Skylake Y configurations are available - Some won't be until february.

The Macbook will likely be updated in January through March. Don't expect the Macbook Air to be updated anymore.