https://www.eurogamer.net/articles/2018-05-18-kingdom-hearts-3
I'd say the possibilities of getting a release date at E3 are very high.
But I'm calling the release will be delayed at least once.
There was no firm release date announced at the Kingdom Hearts 3 Premiere event, but Nomura's official statement was that an announcement should be coming "early next month," so, probably just before E3. Nomura continued, "Kingdom Hearts 3 is a title with many people working on it, so we are making final adjustments, but we are pretty firm on a certain date so we hope to reveal it next month." And as far as we can tell, they're sticking with a 2018 window, so if we were to guess, we'd say a November release date is looking fairly likely at this point.
I'd say the possibilities of getting a release date at E3 are very high.
But I'm calling the release will be delayed at least once.