beautNZphoto: The problem is nothing to do with smart phone sales or declining p&s or dslr sales. ...its basic photographic math. ....photography is all.about LIGHT the small lenses on the smartphone or p&s CANNOT REPLICATE THE LEVEL OF LIGHT of a dslr...period.....and second.....the sensors are physically smaller.....regardless of megapixel count....to get a three quarter size or full frame sensor in a phone or compact means drastic redesign.....as the sensors are LARGER.....they take up more real estate so LESS room for the other components.....yes you can argue mount adapters for the NEX or similar that allow LARGER DSLR LENSES.....but again.....the size of the sensor is physically smaller...its oike trying to fit a v8 into a mini you might have the grunt (megapixels) but you dont have the handling (performance)......
...as others here have posted; The soccer mom's, the folks at their kids classroom events, the little league baseball coaches, the grandparents, etc are all using smartphones nowadays.
They are convenient. They fit in a pocket or a purse. They are always connected to the internet facebook, twitter and instagram. DSLRs are large, bulky and heavy (and expensive). There is also the added benefit of buying into a DSLR system and watching the value of your thousand dollar camera decline as newer models come out year after year.
Yes - you are correct DSLRs capture more light however, Verizon, Sprint, AT&T (and others) are all capturing more (potential camera) users.
IMHO, that math trumps the photographic math that you mention above.