However, one advantage of the LT1 is that it is relatively light and short at 465lbs and 25.3" tall. Compare that to the 4.4L BMW V8 that weights 503lbs and is 29.6" tall.
Yes, for a V8 that's very light indeed. My sort-of complaint with a V8 isn't so much that it's heavy, but that it's a concentrated mass with a relatively high CG (two banks of cylinders above the crank). It's the most compact way to package eight cylinders, but that's about all it is. As Honda, Porsche, and others remind us daily, there are multiple ways to make 500+ HP, and you don't need eight normally aspirated cylinders to do it.
So what do you get if you go to a blown four or six instead of an NA V8? Well, you don't save much weight over an LT1, but you do get to shift the engine's mass around to more favorable points in the chassis. The turbo (if you're using turbos) doesn't have to sit on top of the engine. Neither do intercoolers, radiators, BOVs, etc. It makes packaging a lot easier if the lump itself is smaller and a lower proportion of total powerplant mass.
That said, I think the NA V8 is going to be around a while longer because it might just be the cheapest and simplest way to make 500+ HP, and price point is a big part of the 'vette's appeal.