Most likely Toyota will put a V8 in whatever the Lexus version of the 4Runner will be called, so that they can 'differentiate the product'.
Hey, I have been there, listening in on a bunch of marketing guys in a room. The basic idea is, you want to have a (profitable) product for every price range that somebody wants to spend. If they want to spend $80k for X and you don't have an X that costs $80k they go to the other brand. Its sad but its true.
Concerning a supercharger, I recall there was a rather long thread, here on this forum, about Toyota TRD was working on a turbo charger, and then 'something happened' and development stopped. If I was a product manager, and I heard that we tried a supercharger and it 'didn't meet expectations or requirements, I would be hesitant to try it again.
So, I agree with most everybody else, most likely the 6th gen 4Runner will have the same engine as the Tacoma.
Do not expect my next post to be serious.