With reduction in weight and the increasing demand for better mpg as it concerns the 'Big 3', I wouldn't be surprised to see the engine become a 'stressed member' of the frame at some point down the road.
But they also have to meet crash standards and that could be a can of worms on a production car.
VERY VERY few of us will ever see 100K miles on our replica, fewer still will be looking to make 1500 horse power (like ONE or TWO?). While it's a worthy goal, it's simply not reality in a marketing sense. How many Shelby alloy V8's are there that are making a 1500 horse power? I've heard of ONE, it makes for good press, cool to contemplate, but I'll pass thank you.