Use of forced induction for GT cars (or lack thereof)

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BMWs move to forced induction for their M cars got me thinking about how the vast majority of 'super cars' continue to use normally aspirated engines. Porsche is a good example of offering a variety of powerplants in the 911 Turbo and 911 GTx models, with the GT3 being the homologation model. It's rare though to have such a wide variety of engine choices in the way Porsche offers things.

So the thought is, with BMW moving to turbo, and one-engine offerings for cars like the GT-R, will the equivalency formulas between NA cars and FI cars need to be adjusted so the performance is within the ball park for each type of power plant?

Hopefully BMWs love of FI doesn't keep the iconic M3 out of LeMans racing for a long time...although we know they are focused on DTM in the near future.