I'm just making a statement. What if it won't? Let's also consider that possibility, even if it's likely not to happen. Saying that it's an obvious move to announce at E3, is just us setting our hopes up high AGAIN. There's no hard evidence to back it up, is there?
If you consider the recent trends for this game and the person who is delivering us all this information, Yes I have no doubt in my mind it won't miss this years E3 2015. In terms of E3, they have to give us an update from a western/worldwide perspective. Not everyone knows about ATRs, however nearly everyone knows about E3. In terms of E3 we haven't gotten an update since E3 2013 ( 2 years).
So Considering these very important facts, I would gauge FFXV to be at E3 2015 to at a 99% probably. Yes there is always a chance (1%) that it won't show up. However, they need to update everyone (at E3 because that's where all gamers are focused on the tv/internet for updates on the game(s) they are looking forward too.)
1) Tabata very open about FFXV ( and type-0 HD)
2) He is even going to small remote areas to promote this game ( with new content!) like the one from Malaysia.
3) From a "full game" perspective, they have shown off this game at TGS/Jump Fiesta 2014.
4) Demos from FF normally signify that the game in question will be released within a year after it's demo release. (from FF history that is)
I am very confident it will show up at E3 2015, now whether or not it will be a full out playable demo with 20 min gameplay walk-through, or just a simple trailer with a lot of interview questions answered is still up in the air.
They seem to be on a promotional run with FFXV constantly giving us FFXV info. I honestly would be surprised if it didn't show it's face at E3 this year.