Most ‘normal’ (point-and-shoot) cameras use really small sensors, no bigger than your thumbnail. In fact, probably smaller. They’re easily at 8 megapixels.
The sensor in my digital SLR is roughly the size of two postage stamps side-by-side. It’s six megapixels. (There are big quality advantages to this, but momentarily disregard them.)
Now consider if you had the ‘pixels per inch’ of the small sensor, but blew it up to the size of the APS-C sensors. I’d estimate you could get at least 50 megapixels.
Necessary? No. Would it require all sorts of upgrades (e.g., buffer) to work? Yes. And would the image quality be on par with an SLR? Nope. Would the lens be the limiting reactant? Possibly. But would it be awesome?