400hp is easily possible. Not sure what you mean about sacrificing torque? The most powerful N/A hp/liter car out there now is also the highest tq/liter as well. Producing hp doesn’t mean sacrificing torque and often leads to more torque. The s2000 people say doesn’t have a lot of toque but it has similar or more torque than just about any 2.0l on the market, it just holds that torque to 9k not 6500.
Anyone can produce green 400hp. That is nothing for today’s technology. Chevy seems to build 7.0l 500hp engines that can get 25+mpg on a 3200lb car. I don’t see why Honda cant built a 400hp v6, + 3 electric motors producing 100+hp that gets better than 30mpg.