Interesting that it's just Wizardmon's hat alone. There's too much significance behind Wizardmon for it not to be a teaser. Though of course, Toei could just be trolling us all...
Though you have to wonder if it's at all possible that he could be reborn. If he was deleted in the Real World, would he not be considered to have been deleted forever with no chance of his coming back? Or would his origin - being ultimately from another dimension's Digital World - have anything to do with it?
It would also be mighty cool if they somehow - however implicitly or explicitly - made a reference to Witchelny and any other dimensions that could be connected to the currently known worlds in the Adventure-verse. I'm not holding my breath though.
On a side note, every time I see new poster art for tri. I continue to be surprised at just how different the art style for the Chosen Children is compared to that seen in the actual movies. e.g. eye sizes in proportion to the faces, or facial shape itself. For instance Jou's face looks so different on this poster versus what he looks like in tri. It's just... jarring I guess. Do they hire different artists for the two? Personally speaking it would be nice to see some consistency there (I like the poster art style much better FTR).