MS has the potential to pull off a Nintendo and actually cause an impact in the event thanks to all the games they've already revealed at the previous E3, but they'll most likely focus on CoD and Halo and throw all that potential away.
Sony, eh, E3 2014 was an absolute disaster for them, I hope this ones better.
Nintendo. Show Metroid teaser, a new 3D Mario trailer, Star Fox and Zelda gameplay, and you win. Easy peacy.
I'm now filled with determination.