I actually think there are several possibilities.
One, they eliminate the MBA branding from the MBA SuperDrive. It is being sold with Mac mini servers that don't have an internal SuperDrive.
Two, they eliminate the MBA branding and release it for all Mac notebooks as an external drive... as it implies the next updates to MB and MBPs will eliminate the worthless optical drive.
Three, they introduce a new design with USB 2.0. Probably still eliminating the MBA branding.
Four, they introduce the same design only with USB 3.0 OR LightPeak. And still eliminating the MBA branding.
Five, they introduce a BluRay/SuperDrive and I believe eliminate the MBA branding from it as to be used with ANY Mac.
Six, the completely eliminate from the lineup. For me, this makes the most sense given Apple's strategy.
I think it will be a combination of several of your points. Too many people need an optical drive still, even when it's just occasionally, so Apple won't remove any option for it completely. I think however that most people by now no longer use their optical drives sufficiently enough to warrant having them in every computer by default..
USB 3.0 and Lightpeak are nice, especially for hard drives and in the case of Lightpeak for basically everything, but I think they are both overkill for just an external optical drive. It would negatively impact compatibility at almost no benefit.. On the other side... The target audience are the buyers of future computers which might not have optical drives in them anymore, not the ones who have them already... So those future computers will have the ports required and the compatibility issue doesn't really exist...
What I think might happens is:
[*]Apple removes the optical drive from all the Laptops and Mac Minis.
[*]They release a new external optical drive targeted optionally for all those computers.
[*]Maybe new connectors, maybe not - not a big deal I think.
I still don't think it will be BluRay capable. Apple doesn't want to support physical media for transporting movies. They won't come late to this party. They simply won't come at all. They are making a point this way. The potential buyers for the external drive are people who still need traditional optical media, and even if it is just to rip an Audio CD into iTunes, or to make a Photo CD for your Grandma with no USB Ports.
About the MBA. I also think like some other people on this forum that it has been targetted too much at thinness instead of lightness. For most people that I know, the fact that it's thin is simply a "wow" thing. It holds no further value though. It can be a nice thing to top the cake so to speak but it shouldn't be the main selling point... What has to be the main selling point is that this notebook is light and maybe even durable. It is for people who use a laptop heavily while on the go. It needs to be rather small and light. Not win any world records in being thin. In my opinion they should put the thinness behind and make it small, light and durable in the first place. Also the original MBA just didn't have enough ports. No Ethernet port was a let down for many... n-Wifi is good yes, but when you wanna transfer some amounts of data a cabled connection is just 10 times faster... And the USB Ethernet was basically useless, since it was - well USB. It also was 100Mbit only which n-Wifi can also reach quite easily these days. Put more ports back in, make it less slim but more light. Maybe you end up around a traditional Macbook and you can scratch the MBA completely. In that case the 11.6" version might make sense that we keep hearing about. Screen size would pretty much be the only thing that differentiates between the Macbook and Macbook Air in that case...