I think Nintendo has the best shot at winning. Heres how:
Nintendo
1. Show a trailer for SMG2 with a bit of in game footage, and have the trailer say the game is coming fall 09
2. Show a trailer for Pikmin 3 with a bit of in game footage, and the the trailer say coming summer 09
3. Show a teaser trailer for Star Fox Wii, but don't specify a date. Demonstrate that motion controls are being used to fly the ship (but that classic and GCN controller can be used) and that it is a rail shooter similar to star fox 64.
4. Show a teaser trailer for a new Legend of Zelda for Wii, and have the trailer say the game is coming fall 2010.
5. Reveal that Kirby, Animal Crossing, Wario Land, Fatal Frame, Disaster, and Kid Icarus will all be coming out this fall.
6. Have a sign the says "Metroid Dread", nothing else.
7. Announce that Wii production is being upped another 20%.
-If Nintendo did this they would demolish E3 and be gaurenteed to win this year.
Nintendo could also announce new Wii colors, a $50 price cut for Wii, and a $30 price cut for DS, new DS colors/new DS model (like slim, not all new system)
I think the only aces up Microsft and Sony's sleeves would be $50-$100 price cuts, and slimline versions of their systems. If Nitendo doesn't pull the stops and Sony or Micrsoft put out big price cuts or unexpected new games or something they could still win, but Nintedo is the favorite this year.
What do you think will happen?