@Vikas Well, not entirely. It's not linear. The cost of a camera is not necessarily closely coupled to the cost of the sensor. When a particular semiconductor technology is new, the semiconductor cost is the biggest driver. But as with all things electronic, prices of parts fall, newer better tech comes along. But the interchangeable camera market is quite a bit slower than the pace of electronics tech, because the other expensive factor is lenses: photographers put a lot of money into a...
... camera system (i.e, Nikon F-mount, or Canon EF mount, etc.). So the camera manufacturers work around that. That's why there's always a new camera body for the EF mount, and for the EF-S mount, etc. Because people are already "invested" in the platform.
otherwise, the camera manufacturers would come up with a completely new lens mount system all the time, if they felt people could absorb buying a whole new suite of lenses every few years. They'd love to cater to the churn. But they can't, because decent lenses are expensive to produce, and people don't see a need to change glass all the time (thankfully).