Many years ago, Sony built a digital camera (R1) that had everything you want.
It did not have interchangeable lenses and did not have video.
It sold for $999 and was as large as a DSLR camera.
They did not sell many of them.

There is the law of physics.

i.e. "You can't put 10 pounds of stuff in a one pound box."

The number one obstacle is still waiting for someone to invent a solution.
Getting more light out of a pixel.
There are only about 5 or 6 point and shoot cameras that can perform better in low light than the average point and shoot camera.
All of those are limited to about 3X optical zoom.
While these cameras give you better than average low light performance in a point and shoot camera, they do not come close to the low light performance of DSLR cameras.

Right now the only way to improve the output of a pixel is to increase the size of a pixel.
That means you need a bigger sensor assembly and that means you need a larger diameter lens.

The average DSLR uses a sensor assembly that is about 15 times larger than a point and shoot camera sensor assembly.

I suggest you start looking at the mirror-less cameras.
They have most of the attributes of a DSLR camera in a smaller frame.

http://www.dpreview.com/articles/8986630048/mirrorless-roundup-2011

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