Originally posted by ChristianRock Ricoh has made an interchangeable sensor-based camera before. How well do you think that went? Hint: they abandoned the idea.
That camera combined sensor and lens.
Maybe not everyone would buy this to switch sensors, some would just buy one sensor. But they can pick the one sensor they want. Why are there so many fights about MP? Some people want 12 MP, some want 36. Different needs. Separating body and sensor could make it easier to accommodate for that. Maybe offer another body for the same sensors. One mirrorless, one DSLR.
A cartridge system would make the most sense I guess.
As for IR photography... as long as the sensor itself is unchanged, turn the IR filter into, well, a filter. Make it removable. The cartridge could accommodate that. Take out the sensor (you're able to clean it too that way!) and remove or add the filter, or even use other filters.
The possibilities are endless, the question is if some manufacturer has the balls to do it. I do think it would find a market... I'd be willing to spend a bit more on a camera that offers me that amount of flexibility. Perhaps even if that means changing brands.
@john: But you could take out the sensor, and clean it. Without having to fumble through a long tunnel. You have very easy access to it.
One problem for Pentax would be that stabilizing that thing will be hard. The cartridge will add weight, and that's what you don't want. Also getting rid of the heat will be difficult, though you already have that problem with the SR system. Air cooling perhaps...