Mention of Ace Combat Zero and Ace Combat Online was found in the latest update of the Ace Combat 8 page

If we make any assumptions, it looks like we'll get a pre-order bonus in the guise of a remaster of AC Zero and a full-fledged multiplayer that will come bundled with the main game.Let us remind you that for pre-ordering the last part you were given Ace Combat 5 or 6 as a gift, depending on the platform.

What it really is, we will find out in the future. #game