Hi,
one of the big issue on the device tree will be to update it at runtime from the bootloader
As example the same board have 2 version with only one difference the Main Oscilator. So to support it easly without having 2 DT will want to update the default DT with the proper Osc value from the bootlaoder.
But as the bootloader will not be able to be udpate in the futur on production board, we will have to never change to format of the DT otherwise the bootloder will not be able to work on never kernel.
This is one of issue that nearly all of the PowerPC kernel dev meet ofen with the couple u-boot + kernel + DT
To avoid this we may use a script to update the DT and then specify how we get the information from the bootloader. So in this case, the script we will manage the dependency of the current format version of the DT.
Best Regards, J.