There’s a few more potential considerations.  They could be updating IA because it is competing with Legion, especially seeing as it has a skirmish variant with competitive organised play.  I could see a justification for updating IA to version 2.0 and not offering any sort of upgrade kit for existing products and/or no skirmish rules, specifically to try and draw competitive players into Legion.  If they decide to omit skirmish rules in any potential v2.0, this actually makes their upgrade kits a little easier as they don’t necessarily have to update ALL v1.0 products to v2.0.  If Legion isn’t selling as well as they would like because IA’s skirmish game is eating into the potential audience then it makes sense to only support one and remove the skirmish rules from IA in favour of Legion, which is probably seen as a bit of a Flagship product. You may generate a bit of bad will early doors but it’s definitely something they can come back from – whatever they do someone will whinge.

On the other hand, it may also be that they are going to try and unify Legion and Imperial Assault in the same way that GW and Mantic are now doing with their games.  However I don’t necessarily think this is going to be that easy for FFG because of their use of stat cards that are supplied with the miniatures.  GW and Mantic both use books which can be purchased separately meaning each game is accessible without having to buy the miniatures twice.

And here’s another possibility. Imperial Assault is simply being discontinued.  Maybe they feel they’re spreading themselves too thin or rather spreading the market too thin by having so many Star Wars games.