Since Mazda's dragging its feet on putting the new 2.2L Skyactiv diesel engine in the 6, I doubt we'll see the 1.5L engine in the new 2 much before we see the 2.2 (if we ever see that in the current-gen 6). I think the torque from the diesel engine is impressive and would make the lack of horsepower a smaller issue (more torque would make the engine feel more "meaty," since diesels don't have to rev so high to hit the peak in the power band). The more I look at this car, the less impressed I am with it, but that's just a personal opinion. I know a lot of what made the concept car cool won't make it to production (including, most likely, the engine), and it doesn't look like it pushes the envelope as much as I originally hoped over the current 2, apart from possibly addressing the interior quality issue.
I'm looking forward to news of whether Mazda's going to release a new Mazdaspeed3 or a replacement for the RX-8 in the next couple years. I think one of those two will be what I trade my 2 in for.