I appreciate this would be for iPad Air 2 owners only, but personally I think it would be useful in flight to have SD running on one half of the screen and another app running on the other side.

The answer to your original question is of course "it already does".

We are aware that there are nuances that need to be improved in a multitasking environment, such as the toolbar not properly resizing. We hope to address all of these by the end of the year, but we'll start much sooner than that. We certainly want SkyDemon to behave flawlessly in a multitasking iOS environment.

Great news! Thanks Tim.
Personally I think its a perfect reason for everyone who hasn't done, to go out and buy the iPad air 2.  :-)