factory head unit, amps, etc. vs. 3rd party
 

I doubt anybody has this information, but maybe we can get lucky and somebody will be able to ask this to the right Mazda person. If you want to replace Mazda's head unit with your own (I'd want to plug in my RioCar), then there are really two issues that haven't been addressed in any of the press releases so far.

1) Whether there's a DIN-sized space behind the radio/air control fascia (and how long it will take for third-parties to make new plastic fascias with a DIN-shaped hole in them for folks to drop in third-party stereos). If you look closely at the dashboard pictures, between the stereo knobs and below the CD player slot, it looks suspiciously like there's about a single-DIN blank spot there. If they have the right mounting hardware back there, you could add your own head unit and run the outputs to the existing head unit (and maybe use that TAPE/MD button).

2) Whether the amp is integrated into the head unit, or whether it's a standalone amp.

With my BMW Z3, the stereo was an absolutely standard DIN unit, making it trivial to replace. Interestingly, BMW/Harmon has a special amp in the back, near the spare tire, that has the cross-overs and drives all the speakers. The line level from the head unit to this amp is a totally non-standard 5.6V (versus something "normal" like 4V). The net result in my car is that I have my stereo close to maxxed out to get a sound level that's "loud enough". Of course, they didn't put a gain knob on the amp so you could fix this. And, because the crossovers are integrated with the amp, you can't change it without also replacing all the speakers.

Hopefully, Mazda/Bose uses more standardized parts and line levels. That might let you replace the head unit but otherwise keep the Bose amp/speakers intact (assuming they don't sound like crap).

Bose is traditionally even more difficult to integrate than simply having to overcome the voltage issue (4V is actually even on the high end of the spectrum of most head units, even for those claiming to be "4 volt").

But if you look at the head unit shots, it takes up what appears to be a double-din slot. With that "modular bay" and everything, I don't see any space to include the stock stereo with another DIN sized unit.

---jps