Take this with a grain of salt, but this guy leaked Fallout 76 a few hours before its reveal.
He says that Xbox will announce Forza Horizon 4, Gears of War 5, some Halo game, and Sunset Overdrive 2 at this years E3. And you remember that leak from a couple weeks back where it said that "Yoshi's Flipping Island" was a thing? Apparently that whole leak was accurate.
EDIT: Where I first found out the info
The actual post:
Bethesda is announcing Fallout: Vault 76 : gaming
As I already expressed my thoughts on if it's real or not, let's pretend it's real.
Forza Horizon has been the given, and we have yet to have Halo VI announced, so those two would make sense. Gears, was actually leaked via from within an XBOX a while back.
The surprise here, is Sunset Overdrive having a sequel. It wasn't a financial hit, but man did people love it, including myself. Sunset Overdrive 2, if it is happening, is great, as I loved the first game. My only hope, is that it's on PC, and not only on XBOX (even if I have an XB0).
Now to Nintendo,
If it's Lylat System, that makes me think this is a completely different project from Grand Prix, as Retro actually was doing hiring I think for something revolving already established lore.
Fire Emblem, is Fire Emblem, and considering we had some leaks that were "false", I have doubts. Interested though, as I do think it will be revealed for a Xenoblade release window (betting it's 2018).