Like fix the stupid I2C clock stretching bug. Reverse engineer the Broadcom chip, clone it, and fix the bug, because the lazy asses at Broadcom won't do it.
Or make an RPi with a rich plug-and-play CSI camera ecosystem with hundreds of sensors and lens mounts to choose from, all connected via the camera connector.
Seriously, screw the RPi "high quality" camera and it's teeny useless sensor -- I want 35mm full frame, 20-50 megapixels, in CSI with a python library for exposure control, and I'm willing to pay maybe half the cost of a full frame DSLR to get that.
Nobody sells such a thing at the moment, and it would be an awesome thing to have.