The idea is so obvious, it's amazing it took this long. Toy maker Takara Tomy has taken out ads in this month's hobby magazines showing Optimus Prime with a very familiar color scheme. The details of the Evangelion cross-over is still underwraps at this point, but the ad even includes its own "story":

With Neo-Tokyo 3 in their sights, the Angels slowly advance upon the city...but suddenly a spaceship comes hurtling down from the sky above the Angels: the Autobot Sky Lynx! Out of the ship emerges warriors of the far-off planet Cybertron. They've come to investigate after noticing an unusual energy reading.

"We can't let a disaster like the Second Impact occur on this planet."

"What?! What are these monsters?!"

Optimus Prime sets his sights on an enemy much bigger than himself.