GG does have two teams, but if they're structured the same way Horizon was developed, a new Killzone is ways out. The 2-team structure GG had was a very small preproduction team working on the second project while the bulk of the studio works on the main project.
Bar some secret collaboration where Amsterdam is working with Cambridge on a new Killzone, I don't expect to hear anything about their 2nd project till 2017 earliest.
http://www.neogaf.com/forum/showthread.php?t=976280
Sony Bend's game entered full production January last year. Most big-budget AAA game these days take anywhere from 2 to 2.5 years of full production to get their game out.
Not to mention it's been implied already that Bend suffered through at least 2 cancellation of projects, and what they have now is their 3rd rodeo. In other words, it's very likely close to 2 years of work have gone down the drain.
There's no merit for Sony to hold on a finished game for this long, especially since Sony has been announcing 2017 games like Detroit and Dreams. If it was ready, Sony would clearly prioritise announcing Bend's game over games that aren't finished.
Well, I see Sony holding. Sony has 4 events throughout the year, and while Sony first-party announcements are not equal across the board for all those events, Sony does make an effort to at least have 6-7 big 1st-party announcements for their American/European events, and some bread crumbs for PSX/TGS.