The last time they did an E3 show a few years ago they had alot of games as I recall. This year they have:
-Kingdom Hearts 3
-Shadow of the Tomb Raider
-World Ends With You HD
-FF7 Remake (possibly)
Thing is, all of those could be shown on other E3 shows. Microsoft supposedly has the marketing rights for Tomb Raider so they could show it at Microsoft's conference. They could show KH3 and FF7 Remake at Sony's conference as they have in the past. Octopath and World Ends With You could be shown in the direct or during the treehouse. So why have you own conference? They must have multiple new games to announce. Fingers crossed for Sleeping Dogs 2, the Sleeping Dogs movie is coming next year and it would be great if they had a new game to go alongside it.
you are right, normally they have only their own showcase when they have to show some new games...so lets see what will happen this year