I don't think they'll build a Miata based car with a substantial increase in HP over what you see today. The whole idea is a classic roadster design. Light weight with lower power output. That was the unique thing about our cars. The NA versions fit into that same classic roadster mold and then you had the Turbo cars which offered that increased power output.
But yea, I'd want to take a ride in one of these before passing judgment. I've also heard the 1.4 T in these things has some decent aftermarket potential.