It's 100% impossible for Vita or 3DS to achieve it. So those are out.

With Smash-fest (playing smash bros on best buy! And best part, during MK8 bundle promo) and all the announcements from Ninty, there must be a boost for Wii U. Possibly a very small one, but there has to be one.

Xbox One with so many announcements, and the new 399$ XBone, there clearly should be one.

And lastly PS4... It's hard. The thing is, they announced a new bundle (and it's with Destiny, probably the next 10 million seller in the industry), and that means that a lot of people will buy a PS4 with that bundle + the fact that it's summer release is a port from a 1 year old game. Of course, it will keep selling amazingly. But a notable boost I beilieve won't happen.

And a question to the veterans of VGC... Has this happened before? Or am I just wating my time by thinking this? 

Wii U will sell a bit more than it would have if the Digital Event had been bad, but there will be a drop week-over-week due to the MK8 boost wearing off and sales going back to the previous baseline.

XBOne will sell more thanks to the price drop, should be back to second place, under PS4 but above Wii U.

The biggest boost is probably for X1 but I think all of them will get a slight one.

I hope Wii U and X1 get a huge boost, but it won't happen. So I expect X1 to get a small boost from E3.

XBO will get a boost but that's mainly because of Kinect-less SKU. PS4 will get a massive boost when the Destiny bundle comes out. I don't think anything will change for Nintendo.

"100% impossible for Vita & 3DS"

Is there even such a thing?

That answers my question at the end of the OP

I'd say if any of them were to get one it'd be the Xbone because of the Halo collection

I'm not convinced that E3 really does that much for sales immediately. Only hardcore games keep up with E3 and these people already have a system or already has plan to buy a system at a certain date/game release. The mainstream gamers don't follow E3 much.