Here's a brief summary of what the status of this attraction currently appears to be, based primarily on what insiders - particularly
@Marni1971 - have been saying over on Magic...
- It is extremely unlikely it hits its original target opening of pre-Galaxy's Edge, and there is a plausible worst case scenario where the ride doesn't open until 2020.
- Disney management is apparently aware having it open for the holiday crowds would be very useful for park capacity and operations.
- Its delay does not appear to be the result of an unforeseen technical issue, but rather an intentional choice.
- Rise of the Resistance (currently) should open before it.
So that's where it appears to stand.
I could accept technical problems being reason enough to result in a delay of an attraction. I wouldn't like it, but those things happen in this industry. I have a much harder time accepting pushing the opening back for arbitrary reasons, especially in a park like Hollywood Studios that needs capacity yesterday.