Hey, it was the Jurassic age, the last time I posted...
Sorry, I might never really return... though maybe this summer, for a month, when I'll be struck into bed by a surgery.
I have no reputation, but I must say, that I'm strongly in favor of GE recreated through Blender 3D. I have personal experience with Blender, and it is very advanced, and very usable for this purpose. It is constantly updated, and has no restrictions whatsoever. It's only problem, is it's SO advanced, that the learning curve is only favorable, if you put all your energy into it... I never have, and never really mastered the thing, but I could/can model quite a few things.
But it supports many image and sound formats, like GE, and gives all the control needed. In my opinion, we also must maintain the 2d part of our tool, which I suggest, could be done, by creating prisms in the 3d space, their top and bottom sides forming boundaries of the displayed image, and the hight of the prism allowing for collision detection, the camera shooting right from above. It also opens the way for multiple cameras, which I remember, was once a notable question/feature request. It also may allow for zooming the game itself in and out. And there are ways to do lighting without lights, making the 3d-ness be unnoticed.
About the interface, I think Blender's is brilliant, and the idea of non overlapping panels would be great, and is also simple, but I'd recommend doing whatever is easier to code through Blender's C/C++ or Python.
That's all I can say about that topic... I'm sad I can't be there at the development of the new GE, but I guess you all here have all the capabilities without me anyway.
Good luck!