Question in the title. Scenario being that if my application is a bad build that ends up writing to the last page in flash accidentally resulting in the metadata file at the end of flash being erased.
I had hoped that maybe I could get away with just repairing the pointer to the application, but I don't think that will work since it appears to depend on additional information. I basically use the bootloader block object for the single functionality of assisting in launching into the application. Everything else is set to a custom interface. I have the application validation and bootloader validation turned off. What needs to be done in order for my boot loader to successfully launch a newly loaded application if the metadata file is corrupted?
Well; the obvious response would be not to mess up the metadata 
But, you could try getting the metadata rewritten with the correct data to get running again
Otherwise, if you are trying to continue to the application code without the bootloader using the metadata, I would assume that you would need to modify or rewrite/write-your-own bootloader to run with the different functionality.