The capital ships weren't pushed back. We never got a release window from FFG until a few weeks ago, which is Q2. A May release isn't unreasonable for when they did the preview and put them on the Upcoming list.
And the Upcoming list uses calendar quarters, so Q2 is April - June, and Q3 is July - Sept. Now, I'm willing to accept the possibility that Wave 4 may slip to July, but I'm expecting June. Not quite sure what happened with the Aces, but I doubt these releases will be that late.
If anything is going to release early at Gencon, we will find out about it in May, just like Wave 3.