I think that it would be beneficial to create some new Application Notes to maximise some of the Unique features of the Kinetis series over your competition. The Kinetis series is one of very few Cortex processors that allows the Boot Loader to reside in Flash memory and it is one of the few families where the entire series from the smallest memory size to the largest has Dual Bank Flash.
Current Boot Loader Application Notes cover UART, USB & Ethernet Boot loading.
I would like to see Boot Loader Application Notes specifically using I2C, SPI, CAN, SD card & board level NAND device.
The advantage of a re-programmable Boot Loader is that it provides customers with the ability to create their own Command structure, and with the ability to store keys in the device, its also possible to make the Boot loading secure (encrypted) using One Bank of Flash for the 'new' code, while the other bank is the 'old' code.
The vast majority of your competitor devices have a fixed function, fixed command set and fixed peripheral Boot option, typically using UART0 and less often using SPI.
Regards
Rob