If I look at the advances in sensors and sensor processing that are coming out of the labs and sometimes even shipping in products, I realized something interesting. The game has changed at the research labs. See, previously, the goal was to make a sensor that had the highest resolution. Now, the goal is to still ship sensors with more megapixels but without changing the "real" resolution.
Take, for example, Kodak's image sensor design that adds "white" pixels in between the red, green, and blue. This gives you more light gathering capability at the cost of color resolution. Or take Fuji's always-quirky layouts with smaller "R" pixels for better highlight detail and the more recent version with two identically sized different-sensitivity is the same way. I suspect there's more variations to be had. For example, you could extend Kodak's work and add C,M,Y pixels that would sense two colors per pixel instead of three with a "white" pixel. Or start tessellating sensors like a game of Tetris. Actually, I suspect that with tessellations and pixels sensitive to multiple colors, there might be a way around the moire patterns, thus removing one light-losing layer on the sensor. We're also starting to see cameras that force you to "bucket" pixels at higher ISO settings. Any way you dice it, these will allow you to increase the number of physical megapixels on a sensor while giving you sensitivity and dynamic range more along the lines of a lower resolution sensor. And your level of detail captured will still be excellent, but not as high as a standard bayer-pattern sensor of equivalent resolution. I'm not very fond of the multiple-focal-length camera that allows you to change the focus afterwards, but it also has the same idea.
Yet, this is actually a good thing, paradoxically. It is possible for a company to make a 20 megapixel sensor where "20 megapixel" really means "5 megapixel of real resolution" and for that to be a fairly good, consumer-friendly move on the part of the camera maker that makes everybody happy. Measurebators will be happy because they can shoot their test charts and tell each other stories about how they've got an impressive 20 megapixel sensor. Real photographers will get a camera that has a useful resolution and perhaps better low-light performance and won't worry too much about those extra megapixels because it'll be better than a 15 megapixel camera that doesn't use these weird techniques. And marketers will be happy to pump the number of megapixels up to absurd levels, so they can sell more cameras.