I have read a lot of threads about the MBAs fate and I often wonder... 'Do people want a laptop called Air, or do they want an Intel U Series laptop lighter than a 13in MBP?'
For me, the requirements is simple: I need something much lighter than a 13in MacBook Pro, with a high resolution 13-15in screen, thunderbolt 3, and a U-series or faster processor. The MacBook doesn't cut it. The current line of Core M is the bare minimum of useable performance. You don't need to turn your head far to find people complaining about it.
Intel has various lines of CPUs so that its partners can build various lines of laptops. It is highly unlikely Apple would abandon the U-series chips. The U-series gives companies the ability to deliver excellent performance in a form factor that is highly portable relative to the higher end chips. Core M isn't that... It delivers extreme portability by delivering low end performance.
Apple may never produce another laptop labeled "Air". But they will not abandon the U series line of chips. It would leave a significant gap in their portfolio. I fully expect the Air to be refreshed with Retina, TB3, and possibly wireless charging (A key feature of Skylake). We may even see a 14in screen! The new MBA may even see a radical departure in materials (iPhone 5c).
New MBA or not... there is a gap to be filled by the Intel U series processor. There are amazing laptops being developed with it including some that are lighter than the MBA, with higher res screens, more RAM, etc... Don't expect Apple to give up this space because they have a lighter laptop than the "Air".