Smaller, lighter, but with the same power? No chance. The concept might, but not the production version. Definitely won't be smaller (barring the Mazda2, no car has ever been smaller than the predecessor), lighter maybe but not by much, and the same power is likely to actually be more to keep the marketers happy.
Expect a 2L turbo with some kind of crappy hybrid motor system at best. I don't actually hate the idea of electric motors, but I've yet to see them in a performance car that actually aided performance rather than maintained it (LF, P1 & 918 included). Japaneses don't seem to be able to do big engines with decent economy atm, or at least I can't think of any.