No, a trailer didn't come out. Cool your jets, we've still got a month and a week to E3. :P
I was just snooping around on the official AC websites, and I found myself in the source code for AC7's official website. You can view it by going to view-source:http://ace-7.bn-ent.net/
The website's description can be found on this line:
<meta name="description" content="PS4専用ソフト『エースコンバット7』バンダイナムコエンターテインメント公式サイト">
The description roughly translates to "PS4 exclusive software "Ace Combat 7" official website by Bandai Namco Entertainment".
PS4 exclusive. Sorry, guys :( Of course, this doesn't mean that plans can't change because of the outcry of support from Xbox One players, and please don't stop asking them to port to Xbox One and PC, but right now it's a PS4 exclusive.
EDIT January 26 2017: Welp, no longer the case! Xbox One and PC confirmed!